The partitioning of pyrrole into Nafion membranes in their Na+, Me4N+, and Et4N+ forms has been investigated by electronic absorption spectroscopy and the results are compared with those previously obtained with membranes in the acid form (H-Nafion). In the absence of the acid-catalyzed reactions observed for H-Nafion, pyrrole partitioning into neutral Nafion is weak and follows a simple equilibrium model. The partition coefficients are 1.5 for Na-Nafion, 3.1 for Me4N-Nafion, and 4.0 for Et4N-Nafion. The use of neutral Nafion for the preparation of polypyrrole-modified membranes for direct methanol fuel cells has been shown to have significant advantages over the use of H-Nafion.