This paper describes the electrochemical formation and detection of gold adatoms, by recording successive cyclic voltammograms of a gold electrode in base, and their ability to function as an anchor for phthalocyanine or porphyrin adsorption. The values of the redox potential of the adatom reactions are linked to the redox potential of the adsorbed central metal ion, cobalt or copper, of the phthalocyanine or porphyrin compound. In addition, when using a phthalocyanine or porphyrin immobilized on a gold electrode, the detection of hydroxide can be improved by electrocatalysis. The catalytic current was found to vary linearly with the hydroxide concentration and a detection limit of 11 x 10(-6) mol L-1 for a 5,10,15,20-tetrakis-(4-carboxyphenyl)-porphyrin-Co(II) modified gold electrode could be calculated. (c) 2007 Elsevier Ltd. All rights reserved.