Abstract Cyclic voltammetry was used to probe the electrooxidation of 2-mercaptoethanol on ordinary pyrolytic graphite modified with adsorbed layers of tetrasulphophthalocyanines (TSPc) of several metals. Co—TSPc and Fe—TSPc show the highest activity and they decrease the overpotential of the reaction by ca 0.3 V compared to the bare graphite. Polarization curves obtained on an OPG rotating disc electrode show that the activity of the phthalocyanines of different metals decreases according to Co > Fe> Mn∼Cu>Zn∼Ni>Cu. A plot of activity vs the number of d-electrons in the M—TSPc gives a volcano shaped curve with Co—TSPc on the top. In the light of the kinetic data a mechanism is proposed, which involves a rapid dissociation of a proton from a sulphydryl group in the mercaptan followed by a one electron transfer rate determining step.