A soln.-processable polythiophene, poly((E)-4,4''-didecoxy-3'-styryl[2,2':5',2'']terthiophene) demonstrated large electrochem. induced strain up to 11.5%. Free-standing polymer films were characterised using four-point probe cond. measurements, cyclic voltammetry and electrochem. actuation measurements. Conductivities of .apprx.6 ÃÂ´ 10-5 S/cm (reduced state) or .apprx.1-2 S/cm (oxidised state) were measured. Well-defined polymer oxidn.-redn. responses were obsd. in both the propylene carbonate and acetonitrile electrolytes, with electrochem. efficiency of >80% obsd. under ideal conditions. Results obtained suggested that the actuation strain approx. correlates with the size of the anion (i.e. TFSI > PF6 - > ClO4 -) used in the electrolyte. The largest strain .apprx.11.5% was obtained in an electrolyte soln. consisting of 0.1 M Li.TFSI in acetonitrile. The max. strain attainable increased with an increase in the anodic potential applied and decreased with an increase in stimulation frequency or increasing mech. load. Such functionalised polythiophene material has the combined advantage of soln. processability and the ability to produce large strain.