The Suzuki formulation widely used in literature to study the thermal expansion of solids at constant pressure is extended to study the compression of solids at constant temperature. Two slightly different formulations are used and a modified form is proposed on an empirical basis. The Shanker formulation, which has been derived on the similar ground, is also included in the study. It is found that the earlier relations are applicable up to a finite range of pressure. The deviation occurs as the pressure range is increased. The modified relation gives results, which are in better agreement with the experimental data as compared with the earlier relations in the high pressure range for sodiumhalides viz. NaF, NaCl, NaBr and NaI. This demonstrates the validity of the simple relation proposed in the present paper.