Chloroaluminum phthalocyanine (ClAlPc) films sublimed with a high growth rate on can be made to undergo two transformations when the films are in contact with an acidic aqueous solution: transformation I is obtained if the solution contains and transformation H occurs when there is no redox couple in the solution. The short‐circuit photocurrents produced by these two transformations are different. The highest (1.1 mA cm−2), under 100 mW cm−2white light illumination, was measured for transformation I . An investigation of the differences between the initial and the highly photoactive film shows that transformation I induces the growth of an 840 nm band in both absorption and action spectra. Moreover, IR spectroscopy suggests that there is a possible protonation of a peripheral nitrogen of the phthalocyanine macrocycle. This explains the pH‐dependent kinetics of transformation I , which is larger at lower pH. μ‐oxo‐dimeric aluminum phthalocyanine (PcAlOAlPc) and ClAlPc deposited at a slow growth rate can undergo transformation I but to a lesser extent than high growth rate ClAlPc. Their photoactivities are smaller and their characteristics indicate an increase of after transformation of the film, as in the case of the high growth rate ClAlPc. A fluoroaluminum phthalocyanine film does not undergo any transformation I upon contact with an acidic aqueous solution. Also, there is no rectification for this film and its photoactivity is very low. Scanning electron micrographs (SEM) reveal morphology differences between films of different phthalocyanines but no differences are observed by SEM, for the phthalocyanine films, before and after transformation I or H.