diff --git a/crates/engine/src/cmd/format.rs b/crates/engine/src/cmd/format.rs
index 86870206..17cdc1b1 100644
--- a/crates/engine/src/cmd/format.rs
+++ b/crates/engine/src/cmd/format.rs
@@ -4,7 +4,7 @@
 use deckcraft_model::edit as ed;
 use deckcraft_model::resolve;
 use deckcraft_model::text::{Align, Anchor, AutoFit, Bullet, Caps, ParaProps, RunProps, Spacing, Strike, TextDir};
-use deckcraft_model::{Effects, Fill, Line, Shape};
+use deckcraft_model::{ColorRef, ColorTransform, Effects, Fill, Line, SchemeSlot, Shape};
 use serde_json::{Value, json};
 
 use super::text::{format_body, format_para, format_run};
@@ -50,6 +50,15 @@ pub fn specs() -> Vec<CommandSpec> {
             has_text_or_shapes,
             color
         ),
+        cmd!(
+            "format.textTransparency",
+            "Text Transparency",
+            ["Shape Format", "WordArt Styles"],
+            None,
+            "{value: 0..1} — 0 opaque, 1 invisible; keeps the text's colour (inherited colours included)",
+            has_text_or_shapes,
+            text_transparency
+        ),
         cmd!("format.highlight", "Text Highlight Color", ["Home", "Font"], None, "{color? (absent = none)}", has_text_or_shapes, highlight),
         cmd!(
             "format.case",
@@ -295,6 +304,41 @@ fn color(s: &mut Session, p: &Value) -> Result<Value> {
     let c = color_param(p, "color").ok_or_else(|| bad("format.color", "missing or invalid `color`"))?;
     format_run(s, &move |r| r.fill = Some(Fill::solid(c.clone())))
 }
+/// `a:alpha` for `transparency` (0–1) on `c`, replacing any alpha it had; fully opaque drops it.
+fn with_transparency(c: &mut ColorRef, transparency: f64) {
+    c.mods.retain(|m| !matches!(m, ColorTransform::Alpha(_)));
+    if transparency > 0.0 {
+        c.mods.push(ColorTransform::Alpha(((1.0 - transparency) * 100_000.0).round() as i32));
+    }
+}
+
+/// Text Fill › Transparency: the text keeps its colour and gets an alpha. A run without its own
+/// fill takes the colour it shows now (from the placeholder, master or theme) so only its
+/// opacity changes.
+fn text_transparency(s: &mut Session, p: &Value) -> Result<Value> {
+    let v = f64_param(p, "value").ok_or_else(|| bad("format.textTransparency", "missing `value` (0–1)"))?;
+    if !v.is_finite() {
+        return Err(bad("format.textTransparency", "`value` must be a number from 0 to 1"));
+    }
+    let v = v.clamp(0.0, 1.0);
+    let shown = match current_run(s).fill {
+        Some(f @ (Fill::Solid { .. } | Fill::Gradient(_))) => f,
+        _ => Fill::solid(ColorRef::scheme(SchemeSlot::Tx1)),
+    };
+    format_run(s, &move |r| {
+        let mut f = match &r.fill {
+            Some(f @ (Fill::Solid { .. } | Fill::Gradient(_))) => f.clone(),
+            Some(Fill::None) => return,
+            _ => shown.clone(),
+        };
+        match &mut f {
+            Fill::Solid { color } => with_transparency(color, v),
+            Fill::Gradient(g) => g.stops.iter_mut().for_each(|st| with_transparency(&mut st.color, v)),
+            _ => {}
+        }
+        r.fill = Some(f);
+    })
+}
 fn highlight(s: &mut Session, p: &Value) -> Result<Value> {
     let c = color_param(p, "color");
     format_run(s, &move |r| r.highlight = c.clone())
diff --git a/crates/engine/src/tests.rs b/crates/engine/src/tests.rs
index 059becd1..af0cbe5d 100644
--- a/crates/engine/src/tests.rs
+++ b/crates/engine/src/tests.rs
@@ -1265,3 +1265,36 @@ fn shape_effects_props_adjust_shadow_glow_and_reflection() {
     assert!((r.start_alpha - 0.7).abs() < 1e-9);
     assert_eq!((r.end_pos, r.dist, r.blur), (1.0, 5.0, 0.5));
 }
+
+/// Text Fill › Transparency (#32): the text keeps its colour, own or inherited, and gets an alpha;
+/// 0 makes it opaque again, and it is one undo step.
+#[test]
+fn text_transparency_keeps_the_colour_and_sets_alpha() {
+    use deckcraft_model::{ColorTransform, Fill};
+    let mut s = session();
+    let r = s.execute("shape.insert", &json!({"preset": "rect", "rect": [100, 100, 200, 100], "text": "Hi"})).unwrap();
+    let id = deckcraft_model::ShapeId(r["id"].as_u64().unwrap() as u32);
+    let fill = |s: &Session| {
+        let st = s.doc().unwrap();
+        st.shape(id).unwrap().text.as_ref().unwrap().paragraphs[0].runs[0].props.fill.clone()
+    };
+    // Inherited colour: the run gets the colour it showed, now 25% transparent.
+    s.execute("format.textTransparency", &json!({"value": 0.25})).unwrap();
+    let Some(Fill::Solid { color }) = fill(&s) else { panic!("solid fill expected: {:?}", fill(&s)) };
+    assert!((color.alpha() - 0.75).abs() < 1e-9, "{color:?}");
+    // Its own colour stays; the alpha is replaced, not stacked.
+    s.execute("format.color", &json!({"color": "#C00000"})).unwrap();
+    s.execute("format.textTransparency", &json!({"value": 0.6})).unwrap();
+    s.execute("format.textTransparency", &json!({"value": 0.5})).unwrap();
+    let Some(Fill::Solid { color }) = fill(&s) else { panic!() };
+    assert_eq!(color.base, deckcraft_model::ColorBase::Rgb { rgb: deckcraft_model::Rgba::rgb(0xC0, 0, 0) });
+    assert_eq!(color.mods.iter().filter(|m| matches!(m, ColorTransform::Alpha(_))).count(), 1);
+    assert!((color.alpha() - 0.5).abs() < 1e-9);
+    s.execute("format.textTransparency", &json!({"value": 0})).unwrap();
+    let Some(Fill::Solid { color }) = fill(&s) else { panic!() };
+    assert!(color.mods.is_empty(), "opaque drops the alpha: {color:?}");
+    s.execute("edit.undo", &json!({})).unwrap();
+    let Some(Fill::Solid { color }) = fill(&s) else { panic!() };
+    assert!((color.alpha() - 0.5).abs() < 1e-9);
+    assert!(s.execute("format.textTransparency", &json!({})).is_err());
+}
diff --git a/crates/pptx/tests/roundtrip.rs b/crates/pptx/tests/roundtrip.rs
index fdcd2406..bce9a809 100644
--- a/crates/pptx/tests/roundtrip.rs
+++ b/crates/pptx/tests/roundtrip.rs
@@ -1198,3 +1198,19 @@ fn an_embedded_font_list_already_in_the_package_is_read() {
     assert!(f.panose.is_none() && f.regular.is_none() && f.italic.is_none() && f.bold_italic.is_none());
     assert_eq!(p.media(f.bold.expect("bold")).expect("media").data.as_slice(), font);
 }
+
+/// Text transparency (#32) is `a:alpha` on the run's colour, and survives a save.
+#[test]
+fn text_transparency_round_trips() {
+    use deckcraft_engine::Session;
+    let mut s = Session::with_new();
+    s.execute("shape.insert", &serde_json::json!({"preset": "rect", "rect": [100, 100, 200, 100], "text": "Hi"})).unwrap();
+    s.execute("format.color", &serde_json::json!({"color": "#336699"})).unwrap();
+    s.execute("format.textTransparency", &serde_json::json!({"value": 0.4})).unwrap();
+    let doc = s.doc().unwrap().doc.clone();
+    let bytes = deckcraft_pptx::export(&doc).unwrap();
+    let back = deckcraft_pptx::import(&bytes).unwrap();
+    let sh = back.slides[0].shapes.iter().find(|sh| sh.text.as_ref().is_some_and(|t| t.text().contains("Hi"))).unwrap();
+    let Some(deckcraft_model::Fill::Solid { color }) = &sh.text.as_ref().unwrap().paragraphs[0].runs[0].props.fill else { panic!() };
+    assert!((color.alpha() - 0.6).abs() < 1e-9, "{color:?}");
+}
diff --git a/crates/ui-egui/src/panes.rs b/crates/ui-egui/src/panes.rs
index fe4fa427..e877b34f 100644
--- a/crates/ui-egui/src/panes.rs
+++ b/crates/ui-egui/src/panes.rs
@@ -244,6 +244,13 @@ fn format_shape(app: &mut SlideApp, ui: &mut Ui) {
             ui.data_mut(|d| d.insert_temp(id, (sh.descr.clone(), alt)));
         }
         "text" => {
+            ui.label(egui::RichText::new("Text Fill").font(theme::bold(13.0)));
+            color_button(app, ui, "Color", None, |c| match c {
+                Some(c) => ("format.color".into(), json!({"color": cref_param(&c)})),
+                None => ("format.color".into(), json!({"color": "tx1"})),
+            });
+            text_transparency_slider(app, ui, &sh);
+            ui.add_space(6.0);
             ui.label(egui::RichText::new("Text Box").font(theme::bold(13.0)));
             ui.horizontal(|ui| {
                 ui.label("Vertical alignment");
@@ -837,3 +844,30 @@ fn designer(app: &mut SlideApp, ui: &mut Ui) {
         }
     }
 }
+
+/// The transparency (0–1) of a shape's first text run as stored on it.
+pub(crate) fn text_transparency_of(sh: &deckcraft_model::Shape) -> f64 {
+    let run = sh.text.as_ref().and_then(|t| t.paragraphs.iter().flat_map(|p| p.runs.iter()).next());
+    match run.and_then(|r| r.props.fill.as_ref()) {
+        Some(Fill::Solid { color }) => 1.0 - color.alpha(),
+        Some(Fill::Gradient(g)) => g.stops.first().map_or(0.0, |s| 1.0 - s.color.alpha()),
+        _ => 0.0,
+    }
+}
+
+/// Text Fill › Transparency, as in PowerPoint's Format Shape › Text Options (#32).
+pub(crate) fn text_transparency_slider(app: &mut SlideApp, ui: &mut Ui, sh: &deckcraft_model::Shape) {
+    ui.horizontal(|ui| {
+        ui.label("Transparency");
+        let id = ui.id().with(("text-transparency", sh.id));
+        let stored = (text_transparency_of(sh) * 100.0) as f32;
+        let mut v: f32 = ui.data_mut(|d| d.get_temp(id).unwrap_or(stored));
+        let r = ui.add(egui::Slider::new(&mut v, 0.0..=100.0).suffix("%"));
+        if r.drag_stopped() || r.lost_focus() || (r.changed() && !r.dragged()) {
+            let _ = app.run("format.textTransparency", json!({"value": v as f64 / 100.0}));
+            ui.data_mut(|d| d.remove::<f32>(id));
+        } else if r.dragged() {
+            ui.data_mut(|d| d.insert_temp(id, v));
+        }
+    });
+}
diff --git a/crates/ui-egui/src/ribbon.rs b/crates/ui-egui/src/ribbon.rs
index 7c99f1be..699dea55 100644
--- a/crates/ui-egui/src/ribbon.rs
+++ b/crates/ui-egui/src/ribbon.rs
@@ -1954,6 +1954,10 @@ fn shape_format(app: &mut SlideApp, ui: &mut Ui) {
                     if let Some(Some(c)) = widgets::color_grid(ui, &sc, None) {
                         run(app, "format.color", json!({"color": cref_param(&c)}));
                     }
+                    if let Some(sh) = app.session.active().and_then(|d| d.selected_shapes().first().map(|s| (*s).clone())) {
+                        ui.separator();
+                        crate::panes::text_transparency_slider(app, ui, &sh);
+                    }
                 });
             }
             let (_, a) = small_button_ex(ui, Icon::TextOutline, "Text Outline", sel, false, true);