In this research a comparative study of the starting unit chain length effect on the electropolymerization of thiophene or its oligomers was carried out considering mono (1Th), bi (2Th), ter (3Th), tetra (4Th) and sexi (6Th)-thiophene as starting units. The deconvolved transient allows stating that the growth of polythiophene (PTh) employing each of the starting units have the same predominant contribution to the nucleation and growth mechanism (NGM). The others contributions disappear as the length of the starting unit chain increase. The results were validated by scanning electron microscopy (SEM) of PTh deposits obtained onto SnO2 coated glass, following a potential pulse program. Besides of corroborating the electropolymerization model, this study suggested the possibility of designing and performing suitable experiments leading to the attainment of electro-deposited conductive polymers bearing a desired morphology, appropriated for prospective applications.