In this paper, we present a study on the electrochemical impedance of the n-InP photoanode in 1.2 M HCl, investigating the potential range between almost complete recombination and almost complete photoanodic dissolution. Two features characterize the impedance spectra obtained, i.e., the seeming absence of the recombination impedance and the presence of an inductive loop. Combination of the electrochemical impedance spectroscopy results with Mott-Schottky measurements indicates that the seeming absence of the recombination impedance can be accounted for by assuming that recombination occurs on a rapidly oxidizing decomposition intermediate. Moreover it is argued that, in addition, a slow oxidation step must be present in the overall dissolution process. Together with literature results, these hypotheses are implemented in an impedance calculation. It is demonstrated that the resulting impedance provides a good description of the experimental data, including the presence of the inductive loop. Furthermore, the correspondence between theory and experiment enables us to identify the slow step as the oxidation (by hole capture) of either the fourth or the fifth decomposition intermediate. Therefore, this case study demonstrates that, for the investigation of photoanodic dissolution reactions at n-type semiconductor electrodes, EIS is a technique that provides information complementary to that obtained by other experimental methods (such as IMPS).