diff --git a/README.md b/README.md
index 3b046ca..c7456a3 100644
--- a/README.md
+++ b/README.md
@@ -12,6 +12,7 @@ Run the file `gui.rkt` using *DrRacket* or the `racket` CLI tool.
 - Brainf\*ck interpreter works for the instructions `[`, `]` `+`, `-`, `<`, `>`
   , `.`;
 - Done simple editor GUI with *Run* button and output window.
+- Editor supports basic syntax highlighting.
 
 ## Bugs
 
diff --git a/gui.rkt b/gui.rkt
index 6215bb5..d7382c7 100644
--- a/gui.rkt
+++ b/gui.rkt
@@ -1,7 +1,8 @@
 #lang racket/gui
 
 (require "interpreter.rkt"
-         framework)
+         framework
+         racket/set)
 
 ; The editor width in pixels
 (define EDITOR-WIDTH 600)
@@ -13,7 +14,7 @@
                [width EDITOR-WIDTH]
                [height EDITOR-HEIGHT]))
 
-; execute-content: -> ProgState
+; execute-content: () -> ProgState
 ; Returns the last state of execution of the program loaded in the editor
 (define (execute-content)
   (execute
@@ -21,36 +22,97 @@
     (string->program
      (send editor get-flattened-text)))))
 
-; The run button
+; run-program: Button ControlEvent -> Nothing
+; Given a button and an event, runs the program currently loaded in the editor.
+(define (run-program button event)
+  ; empty output text and set color to running
+  (send run-output set-value "")
+  (send run-output set-field-background run-col)
+
+  ; run the program
+  (define out (prog-state-output (execute-content)))
+
+  ; set output and change color to ended
+  (send run-output set-value out)
+  (send run-output set-field-background end-col))
+
+; Definition of the run button widget
 (define run-btn (new button% [parent f]
                      [label "Run"]
                      ; Callback procedure for a button click:
-                     [callback
-                      (lambda (button event)
-                        ; empty output text and set color to running
-                        (send run-output set-value "")
-                        (send run-output set-field-background run-col)
-
-                        ; run the program
-                        (define out (prog-state-output (execute-content)))
-
-                        ; set output and change color to ended
-                        (send run-output set-value out)
-                        (send run-output set-field-background end-col))]))
+                     [callback run-program]))
 
+; Definition of the editor canves
 (define c (new editor-canvas% [parent f]))
 
-; The editor text object
-(define text-ln% (text:line-numbers-mixin
-                  (editor:standard-style-list-mixin text%)))
-(define editor (new text-ln%))
+; Definition of editor text object. 
+(define text-pro% (text:line-numbers-mixin
+                   (editor:standard-style-list-mixin
+                    (color:text-mixin
+                     (text:basic-mixin
+                      (editor:basic-mixin text%))))))
+(define editor (new text-pro%))
 
 ; Show line numbers in editor
-(send editor show-line-numbers! #t) 
+(send editor show-line-numbers! #t)
 
-; Change font to monospace 16
-(send editor change-style (make-object style-delta% 'change-size 16))
-(send editor change-style (make-object style-delta% 'change-family 'modern))
+; A BFToken is one of:
+; - 'comment
+; - 'instruction
+; - 'shift
+; - 'loop
+; Interp: category of a bf program token
+
+; A BFStyle is one of:
+; - "Comment"
+; - "Instruction"
+; - "Shift"
+; - "Loop"
+; Interp: name of the style for a bf program token
+
+; bf-token->bf-style: BFToken -> BFStyle
+; Given a BFToken, returns the corresponding BFStyle.
+(define (bf-token->bf-style token)
+        (cond [(symbol=? token 'comment) "Comment"]
+              [(symbol=? token 'loop) "Loop"]
+              [(symbol=? token 'shift) "Shift"]
+              [(symbol=? token 'instruction) "Instruction"]))
+
+; bf-lexer: InputPort -> (values 1String BFToken #f Option<Nat> Option<Nat>) 
+; Given an input port, returns the BFToken of the instruction pointed by the
+; port.
+(define (bf-lexer port)
+  (define-values (_ __ pos) (port-next-location port))
+  (define c (read-char port))
+  (cond [(eof-object? c) (values c 'eof #f #f #f)]
+        [else
+         (define 1str (string c))
+         (define bf-token
+           (cond [(set-member? (set "+" "-" "," ".") 1str) 'instruction]
+                 [(set-member? (set "<" ">") 1str) 'shift]
+                 [(set-member? (set "[" "]") 1str) 'loop]
+                 [else 'comment]))
+         (values 1str bf-token #f (+ pos) (+ pos 1))]))
+
+; Syntax highlighting for brainf*ck[(symbol=? token 'loop) "Loop"]
+(send editor start-colorer bf-token->bf-style bf-lexer '())
+
+; Define basic style for instructions (+ - , .)
+(define delta (make-object style-delta%))
+(send delta set-delta-foreground "blue")
+(editor:set-standard-style-list-delta "Instruction" delta)
+
+; Define style for shifting operations (< >)
+(send delta set-delta-foreground "red")
+(editor:set-standard-style-list-delta "Shift" delta)
+
+; Define basic style for looping instructions ([ ])
+(send delta set-delta-foreground "forestgreen")
+(editor:set-standard-style-list-delta "Loop" delta)
+
+; Define style of comments
+(send delta set-delta-foreground "orange")
+(editor:set-standard-style-list-delta "Comment" delta)
 
 ; Running output color
 (define run-col (make-object color% 250 250 200))