Cyclic voltammetric studies of m-nitrobenzene sulphonic acid on a thermally coated Ti/TiO2 electrode in solutions of wide pH range from 5.0 M H2SO4 to 1.0 M NaOH show a pH-sensitive adsorption post-peak in addition to the peak in the potential region of the TiO2/TiOOH surface process. The adsorption post peak appears only between pH -0.43 (1.0 M H2SO4) and pH 5.5. The higher pH limit is close to the isoelectric point of TiO2 reported in the literature. The pH-dependent adsorption is attributed to an acid-base interaction between the protonated TiO2 surface and the sulphonate anionic centre of the aromatic nitrocompound. Below pH -0.43, however, hydrogen evolution swamps the adsorption post-peak.