Abstract
The dressed solitary ion waves in a collisionless unmagnetized plasma composed warm fluid of ion and Boltzmann distributed electrons and positrons are studied. For nonlinear ion acoustic waves, a reductive perturbation method is applied to deduce the KdV equation in terms of first order potential. When soliton amplitude is enlarged, the shape of the wave sidetracks from KdV equation. To improve the soliton shape, the perturbed KdV equation is obtained. The effects of ionic temperature on the electrostatic dressed soliton structures are also discussed.