The n-type polycrystalline pyrite films were obtained by annealing mackinawite electrodeposited on metallic titanium substrates in sulphur atmosphere in the temperature range 523-773 K. The detailed structural and morphological characterisation of the films shows that an increase of crystallite size and a porosity decrease was achieved by increasing the sulphuration temperature. The measurement of thermoelectric effect indicates that pyrite films present n-type conduction, which is attributed to the diffusion of Ti atoms from the substrate. The Seebeck coefficient varies from -54 to -24 muV/K, depending on pyrite grain size. (C) 2003 Elsevier Science Ltd. All rights reserved.