The objective of this study is to demonstrate differences in release rates of chromium, nickel and iron from stainless steel alloys (grade 304 and 316) and pure metals exposed under identical conditions. The study was initiated to fill significant gaps of knowledge on metal release from stainless steels in external constructions [1-2] and to elucidate the difference between estimated release rates from nominal alloy compositions and measured rates.The results are based on laboratory investigations in a specially designed chamber which permits artificial rain to be introduced at a given rain composition and intensity. Metal release rates, and its kinetics as a function of rain duration and volume, were investigated during continuous eight-hour rain events of constant intensity (≈4 mmhr-1) and pH (4.3). In addition, changes in surface composition with time were monitored with XPS for the stainless steel alloys.Selected results from the investigation show the release rate of nickel and iron from stainless steel alloys to be significantly lower than rates from the pure metals. Similar release rates of chromium are seen from stainless steel alloys and the pure metal as a result of the presence of a chromium-rich passive film on both surfaces. The proportion of release rates between chromium and nickel (<1) differs significantly from the corresponding bulk ratio (>1.5).