Department of Chemistry, University of Kalyani, Kalyani-741 235 Manuscript received 29 June 1987, accepted 27 January 1988 Using Henderson's hard sphere fluid equation of state In equation α/βc = pZOҠ, the values of hard sphere diameter a of argon have been evaluated at several temperatures (84-90 K). The residual thermodynamic properties, namely, pressure (P*), Helmholtz free energy (F*), internal energy (U*) and entropy (S*) have been calculated for Henderson's hard sphere fluid and compared with those calculated by Wilhelm for Carnahan- Starling bard sphere fluid. The results agree with one another for values of Vo/V ≤ 0.6. Beyond V0/ V=0.6 the results begin to disagree increasingly in the higher liquid density range,