Propagation of an ion acoustic soliton in a plasma consisting of two warm ion species and hot isothermal electrons is considered, using multiple space time variables in the reductive perturbation method. Expressions have been derived for first and second order potentials. Behaviour of the amplitude of the core part of the soliton shows that initially it decreases rapidly as the light ion concentration increases, assumes a minimum value, and then gradually attains maximum value at α = 1. It has been observed that the soliton may not exist in a certain range of light ion concentration determined by the mass ratio and temperature of ions. The velocity and the width of the soliton are also studied as function of its amplitude.
