diff --git a/mapytex/calculus/core/tree2txt.py b/mapytex/calculus/core/tree2txt.py
new file mode 100644
index 0000000..82f4dcd
--- /dev/null
+++ b/mapytex/calculus/core/tree2txt.py
@@ -0,0 +1,73 @@
+#! /usr/bin/env python
+# -*- coding: utf-8 -*-
+# vim:fenc=utf-8
+#
+# Copyright © 2017 lafrite <lafrite@Poivre>
+#
+# Distributed under terms of the MIT license.
+
+def plus2txt(left, right):
+    """ + rendering
+
+    >>> from .MO import mo
+    >>> plus2txt(mo.MO(2), mo.MO(3))
+    '2 + 3'
+    >>> from .tree import Tree
+    >>> t = Tree.from_str("1+2")
+    >>> plus2txt(t, mo.MO(3))
+    '1 + 2 + 3'
+    """
+    try:
+        left.node
+    except AttributeError:
+        left_ = left.__txt__
+    else:
+        left_ = tree2txt(left)
+    try:
+        right.node
+    except AttributeError:
+        right_ = right.__txt__
+    else:
+        right_ = tree2txt(right)
+
+    return f"{left_} + {right_}"
+
+
+
+def minus2txt(left, right):
+    pass
+
+def mul2txt(left, right):
+    pass
+
+def div2txt(left, right):
+    pass
+
+def pow2txt(left, right):
+    pass
+
+OPERATOR2TXT = {
+        "+": plus2txt,
+        "-": minus2txt,
+        "*": mul2txt,
+        "/": div2txt,
+        "^": pow2txt,
+}
+
+def tree2txt(tree):
+    """ Convert a tree into its txt version
+
+    It calls __txt__ to render MOs.
+
+    >>> from .tree import Tree
+    >>> t = Tree.from_str("2+3*4")
+    >>> tree2txt(t)
+    "2 + 3 * 4"
+    """
+    return OPERATOR2TXT[tree.node](tree.left_value,  tree.right_value)
+
+
+# -----------------------------
+# Reglages pour 'vim'
+# vim:set autoindent expandtab tabstop=4 shiftwidth=4:
+# cursor: 16 del