Hydroxyapatite (HA) was selected as dopant and synthesized by a sonochemical method in this study. PVA–HA–KOH–H2O composite alkaline solid polymer electrolyte (ASPE) was prepared by solution casting method. Two different doping routes, i.e., the physical mixing (PM) and in situ synthesis (ISS) were considered. The influences of the ASPE composition such as HA content, KOH content and water content on the conductivity were investigated. The ASPE prepared by ISS route has a porous structure which is important for ion transfer. Accordingly, the conductivity of the ASPE prepared by ISS is higher than that of by PM. A highest conductivity of about 0.1S/cm is reached for ASPE prepared by ISS route at 70% water content for m(PVA):m(KOH):m(HA)=10:14:10 system, higher than that of by PM route, 0.08S/cm. The nickel/zinc cell shows better electrochemical properties assembled with the ASPE prepared by ISS approach than by PM approach.