The inhibitive effect of Solanum trilobatum leaves extract on the corrosion of aluminium in 1M NaOH solution was studied using weight loss, hydrogen evolution, polarisation and electrochemical impedance spectroscopy methods. The extract acts as an excellent corrosion inhibitor with 94% efficiency at the highest concentration in the alkaline environment and the inhibition efficiency increased with increasing concentration of the extract. Polarisation studies revealed the fact that the leaves extract acted as a mixed type inhibitor. These results were supported by kinetic and thermodynamic parameters for corrosion and adsorption processes calculated from the experimental data at the various temperatures studied.