Department of Chemistry, Himachal Pradesh University, Summer Hill, Shimla-171 005, India Manuscript received 7 December 1998, accepted 9 March 1999 The standard molal potentials (\(E_m^\theta\)) of the cell, Cd-Hg I CdSO4 (m), mannitol (x) I Hg2SO4 (s) I Hg, have been determined in water and 5, 15 and 25% aqueous mannitol solutions at five different temperatures (298-318 K) and molality of cadmium sulphate ranged from 0.01 to 0.1 mol kg-1. Mean molal activity coefficients at 298 K are calculated. The temperature variation of the standard e.m.f. is used to calculate the standard thermodynamic functions (ΔGθ) for the cell reaction. The primary medium effect of different solvents upon cadmium sulphate and standard quantities of transfer for cadmium sulphate from the standard state in water to that· in the respective aqueous mannitol solutions arc also calculated.