A solid acid membranes based on poly(vinyl alcohol) (PVA), magnesium bromide (MgBr2) and phosphoric acid (H3PO4) were prepared by a solution casting method. The morphological, X-ray and electrical properties of the (PVA)(1−x)(MgBr2)x/2(H3PO4)x/2 solid acid membranes where x = 0.0, 0.1, 0.2, 0.3 and 0.4 wt% were investigated. The PVA polymer electrolyte directly blended with acid salt shows improvement in ionic conductivity and transport properties. The maximum ionic conductivity value of PVA/acid salt polymer electrolyte with x = 0.40 wt% of acid salt is around 1.64×10−4 S cm−1 at 20
C and the ionic transport number (t+) is in the range of 0.98–0.99. In this work, the data shows that the (PVA)(1−x) (MgBr2)x/2 (H3PO4)x/2 solid acid salt membrane is promising for intermediate temperature phosphoric acid fuel cell applications.