Corrosion rate (Progressive) of mild-steel (MS), zinc and aluminum have been determined under outdoor conditions of exposure at Vapi (South Gujarat) representing an industrial environment. Mild steel (MS), zinc and aluminium plates exposed during November 2005 indicates corrosion rate of 791, 131 and 2.4 mg/sq.dm for one month exposure period and 12731, 952 and 29.8 mg/sq.dm for mild steel, zinc and aluminium respectively for twelve months exposure period. Mild steel panels exposed vertically suffer less corrosion than those exposed at an angle of 45?. The resistivity towards the environment was in the increasing order of mild steel < zinc < aluminium. Corrosion rate of these three metals was found more in rainy seasons than the rate of winter and summer season.