The catalytic effect of transition metal ions, i.e. Fe(III), Cu(II), Co(II), Cr(III), Cd(II), Zn(II), Ni(II) and Mn(II) in reaction systems containing hydrogen peroxide and hydroxyl radical scavenger was evaluated at different pH and temperature. The rate of hydroxylation was followed using spectrophotometry and from this rate, the rate of production of hydroxyl radicals was estimated. This rate was shown to correlate with the corrosiveness of metals in paper. The result can be used in studies of the behaviour of transition metals in similar reaction systems, e.g. in nutrition, polymers, or the human body.