The stability constants of 1-(2'-Hydroxy-5'-Bromophenyl)-3-(4'Chlorophenyl)-1,3-Propanedione [HB4CP] (L) with Cr(III) metal ion in different percentage of Dioxane-water, DMF-water and DMSO-water mixtures having varying dielectric constants have been determined pH metrically. The ionic strength (m = 0.1 mol.dm-3) was maintained constant. The stability constants (log k) of binary (1:1) systems found to increase with increase in percentage of Dioxane, DMF and DMSO. The studies of effect of dielectric constants of medium on the stability constants of (HB4CP) and Cr(III) metal ion have also been studied.