Here we have studied the electrocopolymerisation of binary mixtures of functionalised thiophenes in varying compositions and determined independently for each copolymer the spectroelectrochemical responses and the composition of the material using X-ray photoelectron spectroscopy. We have observed strong correlations between the composition of the copolymer material and the composition of the binary solution from which the polymer was grown. In addition, we have shown that the spectroelectrochemical properties of the copolymers indicate the presence of random copolymer material where the lambda(Max) values of the neutral, undoped, polymer scales with composition but also suggest that there may be small amounts of block copolymer or phase-separated mixtures of the homopolymer components.