The possible interrelation between the value of electrode potential φs, surface condition and mechanisms of pore formation of Si was substantiated. The influence of finishing chemical treatment method on the φs of Si-plates was investigated.Features of φs behavior over time in media with different pH values after treatment of Si-electrode in acid-peroxide solutions (including HNO3) are treated by manifestation of incomplete surface passivation by the oxide film. It is caused by the fact that, for the course of reduction-oxidation reactions, it is necessary to reach a certain concentration in the HNO2 catalyst solution, which would "start" the NO2 recyclizationprocess.The research results showed that treatment of Si in ammonia-peroxide solutions promotes the formation of Si-OH coating on its surface. This leads to a larger value and stabilization of the electrode potential in neutral and acidic media. In alkaline medium, hydroxide film can turn into oxide by breaking the bonds O-H that leads to the reduction of potential. According to the Pourbaix diagram analysis, the course of reactions with the formation of ionic forms of orto-silicate acid is probable in this area of pH.