Corrosion susceptibility and inhibition of 12Cr mar tensitic stainless steel was evaluated in different sulphuric acid and the acid chloride concentrations. Corrosion inh ibition of the tested samples in 1M H 2 SO 4 was evaluated using potassium dichromate of different concentrations. T he experiments were performed at ambient temperatur e using potentiodynamic polarization measurement. This pape r reports the observed electrochemical response of the tested samples in the strong acid environments. Potentiody namic polarization resistance technique was used to estimate the corrosion rate, the polarisation resistance and inhibition of the alloy samples tested. The result s obtained showed some varied magnitude of corrosion susceptib ility for the stainless steel at the different H 2 SO 4 concentrations and also in the acid chloride test m edia. Corrosion inhibition of the tested samples wa s effectively achieved using the potassium dichromate inhibitor.