Abstract The electrical conductivity of a pyrolysed cyano-substituted polyamide and of the corresponding diamide, prepared from 1,4-bis(2-cyano-2-carboxyvinyl)benzene, was studied. In particular, the a.c. conductivity of the unpyrolysed polymer, in the form of a thin film with a thickness of 3000 Å, was investigated at room temperature over the frequency range from 40 Hz to 100 kHz. The observed frequency dependence suggests the existence of interfacial polarizations between the bulk and the electrodes, or within the bulk. The d.c. conductivity of the polymer and the corresponding diamide, in the form of pellets, both unpyrolysed and pyrolysed, was investigated over the temperature range from 100 to 600 K. The pyrolysis temperature covered the range from 550 up to 900°C. The effect of pyrolysis duration was also studied at pyrolysis temperatures of 550 and 750°C. The results show that the conductivity of the pyrolysed samples increases enormously with increasing pyrolysis temperature up to 750°C, reaching a value of 2.857 Ω −1 cm −1 at room temperature, while further increase in the pyrolysis temperature results in a decrease of the conductivity. For a pyrolysis temperature of 900°C the conductivity at room temperature has a value of 1.613 × 10 −1 Ω −1 cm −1. The effect of pyrolysis at high temperatures suggests the promotion of formation of a multiphase system, which could also be responsible for the observed behaviour of the conductivity at prolonged, moderately high pyrolysis temperatures. X-ray profiles, recorded for all samples, both unpyrolysed and pyrolysed, support the interpretation of the conductivity results.