diff --git a/rmgpy/constants.pxd b/rmgpy/constants.pxd
index 292ec667ca..491c98a708 100644
--- a/rmgpy/constants.pxd
+++ b/rmgpy/constants.pxd
@@ -25,4 +25,4 @@
 #                                                                             #
 ###############################################################################
 
-cdef double pi, Na, kB, R, h, hbar, c, e, m_e, m_p, m_n, amu, a0, E_h
+cdef double pi, Na, kB, R, h, hbar, c, e, m_e, m_p, m_n, amu, a0, E_h, F
diff --git a/rmgpy/constants.py b/rmgpy/constants.py
index 9e7d0f47f5..212d5c3fca 100644
--- a/rmgpy/constants.py
+++ b/rmgpy/constants.py
@@ -110,6 +110,9 @@
 #: :math:`\pi = 3.14159 \ldots`      
 pi = float(math.pi)
 
+#: Faradays Constant F in C/mol
+F = 96485.3321233100184
+
 ################################################################################
 
 # Cython does not automatically place module-level variables into the module
@@ -130,4 +133,5 @@
     'm_n': m_n,
     'm_p': m_p,
     'pi': pi,
+    'F': F
 })