Zn dissolution and passivation in buffered phosphate electrolyte in the pH range between 7 and 13.5 has been studied under a wide variety of experimental conditions. The electrode rest potential shows three regions depending on pH. Between pH 7 and 10 a constant value was found while a slope of 60 mV is obtained from a plot of Er vs. pH. In the pH range 10–11.5 a mixed potential could be established due to the minimum buffer capacity of the system. The necessary charge for passivation was found to be 1.5 mC cm−2 and this was attributed to a monolayer film. From l.s.v. and RDE results a change on Zn dissolution mechanism from a dissolution precipitation to a solid phase process with pH can be postulated. Time and potential effects on product reduction would show that there are chemical transformations on the electrode surface as a second step on the electrode poassivation. From experimental kinetic parameters an empirical rate equation for Zn dissolution is found as ia=2kaFcOH−c(PO43−)t0.5exp[(3/2)EF/RT)] Accordingly a reaction mechanism is postulated where PO43− ions act as dissolution promoters, while HPO42−, through the formation of NaZnPO4·H2O glass, would act as a dissolution inhibitor.