In the VVER-type pressurised water nuclear reactors, the so-called AP-CITROX method (AP: alkaline permanganate; CITROX: citric and oxalic acids) is widely used for the chemical decontamination of the austenitic stainless steel piping in steam generators. In the present work we report some new findings obtained by voltammetric, gravimetric, gamma -spectrometric, surface spectroscopic (SEM-EDX) and in situ radiotracer studies of the passive layers formed on austenitic stainless steel type 08XI8H10T (GOST5632-61) during the surface decontamination by the AP-CITROX procedure. The experimental results reveal that the AP-CITROX decontamination procedure, performed even in three consecutive cycles, does not exert detrimental corrosion effects, but rather substantially improves the passivity of the surface oxide layer.