Electrically conducting blends, based on polypyrrole (PPy) as the conductive polymer and poly(epsilon-caprolactone) (PCL) as an insulating polymeric matrix, were prepared by polymerizing pyrrole (Py) in its vapor state inside the PCL matrix. The roles of specific interactions between blend components as well as the crystallization of PCL matrix in the resulting morphology have been analyzed by Fourier-transform infrared spectroscopy (FTIR), thermo-optical analysis (TOA) and atomic force microscopy (AFM). The results indicate that PPy is located within both the intra and interspherulitic regions of the PCL matrix achieving a well-developed connected network. Compared with amorphous matrices, considerable conductivity (around I S/cm) was raised with the crystalline PCL matrix with only a relatively low level of the conductive polymer (similar to 5%) in the blend. (c) 2006 Elsevier Ltd. All rights reserved.