In the present paper, we have investigated the high-pressure structural phase transition of yttrium pnictides (YX; X = N, P, As and Sb). An extended interaction potential (EIP) model has been developed (including the zero point energy effect in three body interaction potential model). Phase transition pressures are associated with a sudden collapse in volume. The phase transition pressures and associated volume collapses obtained from present potential model show a generally better agreement with available experimental data than others. The elastic constants and their pressure derivatives are also reported. Moreover the thermo physical properties have also been obtained successfully. Our results are in general in good agreement with experimental and theoretical data where available, and provide predictions where they are unavailable. (C) 2010 Elsevier B.V. All rights reserved.