The effect of ionic temperature on ion-acoustic solitons in a warm, two-ion plasma consisting of negative ions and non-isothermal electrons are studied by using the reductive perturbation method. The basic set of fluid equations are reduced for fast ion-acoustic waves and slow ion-acoustic waves to the modified Korteweg-de Vries equation. A stationary solution of this modified Korteweg-de Vries equation is obtained and the effect of ionic temperature on ion-acoustic solitons is investigated.