Development of proton conducting membrane electrolyte is one of the most important research area within the domain of direct methanol fuel cells (DMFCs). This study reports the preparation of glutaraldehyde-crosslinked poly(vinyl alcohol-co-styrenesulfonic acid) proton exchange membrane (PEM) for DMFC. In order to understand the effect of the extent of crosslinking on the PEM properties, varying concentration of glutaraldehyde was used. Key properties of PEMs such as water uptake, swelling behavior, ion-exchange capacity, proton conductivity, and methanol permeability were thoroughly analyzed. PEM formed using 0.5 M glutaraldehyde solution resulted in a crosslinked PEM with the moderate properties, such as swelling, water uptake, proton conductivity and mechanical strength, along with the exhibition of high proton conductivity and lower methanol permeability compared to commercial Nafion-117. In addition, optimized PEM produced a peak power density of 58 W/m2 at a current density of 300 A/m2, when DMFC fed with 2 M methanol solution at 60 °C.