Highly transparent (>80%) and conductive layers (10(-6) S/cm) were obtained by the pulsed plasma polymerization of thiophene. The influence of power, pressure, pulse time, duty cycle, and position in the reactor on the conductivity of the resulting plasma polymerized thiophene (PPT) layers was evaluated. In the used ranges, only pressure had a significant influence on the conductivity of the deposited layer. The results could be correlated to the effect of the deposition parameters on the fragmentation of the thiophene monomer. At high pressure there was less fragmentation of thiophene, resulting in a higher conductivity of the layer. It was shown that the use of a pulsed plasma as a means to minimize fragmentation is most efficient when the off time is chosen such that the reactor is replenished with new monomer during the off period.