Stainless steel 304L is being considered as a structural material for a component in a critical facility in an environment of molten lead–bismuth eutectic (LBE) at a temperature between 250 and 350 °C. This paper gives results on the effect, of 10,000 h exposure to non-isothermal liquid LBE at temperatures of 250 and 350 °C, on the mechanical and structural properties of SS 304L. The dissolved oxygen concentration in the molten eutectic was 4 X 10^-10 wt% and flow velocity was 16 cm/s. In order to assess the changes in mechanical properties tensile tests  were carried out in air at 25 °C and fractography of fractured surface was observed by scanning electron microscopy. The results showed no change in the mechanical properties of SS 304L after 10,000 h exposure to LBE at 250 and 350 °C. Electron probe microanalysis of the interface of SS 304L with LBE showed that there was no penetration of LBE into the grain boundaries nor preferential  dissolution of any of the components of steel in LBE after 10,000 h exposure at either temperature. No oxide layer was observed on the surface of SS 304L.