Propagation of ion‐acoustic solitary waves in a warm plasma with negative ions under the drifting effect of electrons is considered. Compressive and rarefactive solitons are shown to exist depending on the drift velocityv’eof electrons for different values ofQ’(mj/mi—negative to positive ion mass ratio) ≥1 or ≤1. The amplitude of the compressive soliton forQ’≥1 and rarefactive soliton forQ’≤1 but small, is found to be greatest nearv’e= 0 whenr(=nj0/ni0, negative to positive ion number density ratio) ≤0.5, showing thereby the characteristic change in solitons for the inclusion ofv’e.