The results presented in this paper were obtained with three Al–Sn binary alloys (0.09, 0.2 and 0.4wt.% Sn, respectively) that had been prepared on super pure (99.999%) Al base. The yield of hydrogen evolved during cathodic polarisation of Al–Sn alloys in a 2M NaCl solution was measured volumetrically as a function of current density, temperature and tin content in the alloy. The yield was established to be somewhat below 2 at all current densities and at low temperatures, while with increasing temperature it approached the value of 4. With the increase of tin content in the alloy, the yield of hydrogen decreases, which depends on the degree of hyperactivity that occurs in Al–Sn alloys in the region of high cathodic potentials.