diff --git a/components/chemtext/source/chemtext.pas b/components/chemtext/source/chemtext.pas
index d3bbf02fa..ffae3faf4 100644
--- a/components/chemtext/source/chemtext.pas
+++ b/components/chemtext/source/chemtext.pas
@@ -24,6 +24,16 @@ interface
 uses
   LclIntf, LCLType, LCLVersion, Types, SysUtils, Classes, Graphics, StdCtrls;
 
+const
+  DEFAULT_SMALLFONT_SIZE = 67;
+  DEFAULT_SUBSCRIPT_OFFSET = 50;
+  DEFAULT_SUPERSCRIPT_OFFSET = 25;
+
+var
+  SmallFontSizePercent: Integer = DEFAULT_SMALLFONT_SIZE;
+  SubscriptFontOffsetPercent: Integer = DEFAULT_SUBSCRIPT_OFFSET;
+  SuperscriptFontOffsetPercent: Integer = DEFAULT_SUPERSCRIPT_OFFSET;
+
 type
   TChemArrow = (
     caASCIISingle, caASCIIDouble, caUTF8, caUTF8Single, caUTF8Double, caUTF8Half
@@ -129,11 +139,15 @@ type
   TArrowDir = (adLeft, adRight, adBoth);
 
 const
-  SUBFONT_SIZE_MULTIPLIER = 75;
-  SUBFONT_OFFSET_MULTIPLIER = 50;
-  SUBFONT_DIVISOR = 100;
   ARROW_LINE: array[boolean] of char = ('-', '=');
+  SUBFONT_DIVISOR = 100;
+
   ESCAPE_CHAR = '\';
+  SAVE_CURRENT_POS = '@';
+  RETURN_TO_POS = '|';
+  SUPERSCRIPT_CHAR = '^';
+  SUBSCRIPT_CHAR = '_';
+
   HYDRATE_DOT = #$E2#$80#$A2;
 
 function ChemTextHeight(ACanvas: TCanvas; const AText: String;
@@ -172,8 +186,8 @@ var
   begin
     h := ACanvas.Font.Height;
     try
-      ACanvas.Font.Height := MulDiv(h, SUBFONT_SIZE_MULTIPLIER, SUBFONT_DIVISOR);
-      yoff := abs(MulDiv(h, SUBFONT_OFFSET_MULTIPLIER, SUBFONT_DIVISOR));
+      ACanvas.Font.Height := MulDiv(h, SmallFontSizePercent, 100);
+      yoff := abs(MulDiv(h, SubscriptFontOffsetPercent, 100));
       if not Measure then
         ACanvas.TextOut(x, y + yoff, s);
       x := x + ACanvas.TextWidth(s);
@@ -186,12 +200,14 @@ var
   procedure DrawSup(var x: Integer; y: Integer; const s: String);
   var
     h: Integer;
+    yoff: Integer;
   begin
     h := ACanvas.Font.Height;
     try
-      ACanvas.Font.Height := MulDiv(h, SUBFONT_SIZE_MULTIPLIER, SUBFONT_DIVISOR);
+      ACanvas.Font.Height := MulDiv(h, SmallFontSizePercent, 100);
+      yoff := abs(MulDiv(h, SuperscriptFontOffsetPercent, 100));
       if not Measure then
-        ACanvas.TextOut(x, y - 1, s);
+        ACanvas.TextOut(x, y - yoff div 2, s);
       inc(x, ACanvas.TextWidth(s));
     finally
       ACanvas.Font.Height := h;
@@ -239,6 +255,7 @@ var
   s: string;
   subNos: boolean;        // "subscript numbers"
   escaping: Boolean;
+  savedX: Integer;
 begin
   Result := Size(0, 0);
   if AText = '' then
@@ -324,11 +341,29 @@ begin
           ESCAPE_CHAR:
             escaping := true;
 
+          SAVE_CURRENT_POS:
+            savedX := X;
+
+          RETURN_TO_POS:
+            X := savedX;
+
+          SUPERSCRIPT_CHAR:
+            begin
+              inc(i);
+              DrawSup(X, Y, AText[i]);
+            end;
+
+          SUBSCRIPT_CHAR:
+            begin
+              inc(i);
+              DrawSub(X, Y, AText[i]);
+            end;
+
           else
             begin
               j := i+1;
               while (j <= Length(AText)) and
-                    not (AText[j] in ['0'..'9', '+', '-', '<', '.', ESCAPE_CHAR])
+                    not (AText[j] in ['0'..'9', '+', '-', '<', '.', ESCAPE_CHAR, SAVE_CURRENT_POS, RETURN_TO_POS, SUPERSCRIPT_CHAR, SUBSCRIPT_CHAR])
               do
                 inc(j);
               s := Copy(AText, i, j-i);