In this communication an attempt has been made to develop the convective mass transfer relation for a doublecondensing chamber solar still (DCS) and a single-sloped conventional solar still (CSS) for different operating temperature ranges. Rigorous experimentations were carried out, on both the DCS and CSS during 1996-97. The
experimental data have been used to discover C and n in Nu = C (Gr.Pr)" by applying linear regression analysis. Based
on the results, it is inferred that (1) the order of C and n are the same as proposed by Dunkle  for low operating temperature ranges and (2) the value of C and n changes for operating temperatures other than Dunkle's.