[ecfisa]

Hola Jose Roman.

Un ejemplo:

Código Delphi [-]
...
implementation

procedure TForm1.FormCreate(Sender: TObject);
begin
  with ListBox1 do
  begin
    Items.Add('8PM');
    Items.Add('10AM');
    Items.Add('12PM');
    Items.Add('2PM');
    Items.Add('4PM');
    Items.Add('5AM');
    Style := lbOwnerDrawFixed;
  end;
end;

procedure TForm1.ListBox1DrawItem(Control: TWinControl; Index: Integer;
  Rect: TRect; State: TOwnerDrawState);
begin
  with TListBox(Control) do
  begin
    if Items[Index] = '12PM' then
    begin
      Canvas.Brush.Color := clRed;    // fondo rojo
      Canvas.Font.Color  := clWhite;  // letra blanca
    end;
    Canvas.FillRect(Rect);
    Canvas.TextOut(Rect.Left, Rect.Top, Items[Index]);
  end;
end;

Saludos.