The voltammetric, morphologic and spectral properties of poly(dihexadecyl-4H-cyclopenta[2,1-b:3.4-b＇]dithiophene), synthesised on ITO electrode in acetonitrile/dichloromethane mixed solvent by cyclic voltammetry, strongly depend on the film thickness. The polymerisation occurs through two successive steps: the electrode covering and a further growing of the film on the polymer coated electrode. The rate of the film growing is higher in acetonitrile-rich solvent and is a linear function of the monomer concentration during both the electrode covering and the subsequent growing step.