The analysis of the reactor safety and environmental protection for sodium cooled fast reactors requires an indepth knowledge of the smoke release behaviour of liquid sodium spillages in accidental conditions. The present study is aimed at experimental determinations of specific smoke release rates resulting from burning of sodium pools in closed as well as in open atmosphere. The pool temperature is controlled by incorporating an integrated cooling and heating facility in the burn-pot. Controlled test atmosphere is effected by regulating the oxygen and moisture content of the combustion chamber. In isothermal conditions (temperature of the pool 600±50°C) oxygen concentrations have a pronounced effect on the smoke release rate which diminishes as oxygen concentration increases. On the other hand, increasing oxygen content results in a slow fall of smoke release rate in non-isothermal conditions until at an oxygen concentration of about 7% (v/v) when there is a modest rise. In open atmosphere the smoke release rates show a rising trend in logarithmic scale with increasing pool area.