Polyaniline is considered one of essential materials used widely in technologies of solar cells, sensors, batteries and membranes. The preparation of polyaniline using chemical polymerization has many essential parameters that have to be controlled during the synthesis process. These parameters include temperature, time of polymerization, type of dopant, type of oxidant, and washing solution treatment. The washing step is an important factor for the removal of short chains produced during polymerization (oligomers), which are concomitant with the polyaniline during polymerization. Moreover, the washing treatment step is vital for getting rid of residual monomer and excess oxidant. polyaniline samples were prepared by using aniline monomer, ammonium persulfate as an oxidant, and acid dopant (hydrochloric acid or phosphoric acid). The prepared polyaniline was washed using different solutions such as water, acid, acetone, and alcohol. FTIR and XRD analyses confirmed the preparation of polyaniline emeraldine salt in all samples. The results showed an improvement in electrical conductivity and yield when two steps treatment by water and acid solutions were used, while acetone and ethanol showed no change in conductivity. The higher conductivity obtained was 7.95x10-2 S/cm when using hydrochloric acid dopant and two-step treatment by water then phosphoric acid.