We report in this study on the simultaneous conductance and cyclic voltammetry measurements during the potentiodynamic electropolymerization of PPy films, incorporating in the polymeric matrix, first, multi-walled carbon nanotubes (MWCNTs), second, cobalt phthalocyanine (CoPc) and finally both compounds simultaneously are herein presented. Four different MWCNTs were studied (diameter 30 +/- 15 nm and 15 +/- 5 nm, both with lengths of 1-5 mu m and 5-20 mu m). The results indicate that the conductance and compatibility of PPy/MWCNT composites is ruled by the quantity of exposed anionic groups on the MWCNT surface. Those with the widest diameter have the best performances and also have the largest quantity of anionic groups (carboxylic acids). After incorporation of CoPc, the composite material showed enhanced electrical properties that could be useful in the future as a sensor material in the detection of redox species. (C) 2012 Elsevier Ltd. All rights reserved.