Triphenylmethane derivatives, namely fuchsin basic (FB) and fuchsin acid (FA), were studied for their possible use as copper corrosion inhibitors in 0.001 to 1.0 M sulphuric acid solutions. Benzotriazole (BTA) was also tested for comparative purposes. These inhibitors were studied in concentrations from 1×10−5 to 1×10−1 M at temperatures from 298 to 328 K. The gravimetric method was employed to study the protective effect of FB, FA and BTA. The order of inhibition efficiency was BTA>FB>FA. Up to nine adsorption isotherms were tested to fit the experimental data. The best fit was obtained using the Frumkin isotherm model. A thermodynamic/kinetic model of adsorption was also fitted. The projected molecular area of the inhibitors was calculated to elucidate inhibitor orientation in the adsorption process.