Ba3-xKxHx(PO4)2 is a candidate solid-state proton conductor for solid acid fuel cells that is water-insoluble. The measured conductivity of ∼ 2.4 10-5 S cm-1 for the composition x=0.80 at 250°C is not competitive for solid acid fuel cell applications. This work investigates a methods for synthesizing solid acid electrolytes with the strategy of increasing proton conductivity by cation substitution and decreasing particle size. We report on the synthesis of nano Ba3-xKxHx(PO4)2 to a novel Ba3-xNaxHx(PO4)2. X-ray diffraction was used to confirm the Ba3(PO4)2 crystal structure and measure lattice strain as a function of cation substitution. SEM confirmed the morphology of micro Ba3-xNaxHx(PO4)2 is substantially different from micro Ba3-xKxHx(PO4)2, suggesting that Ba3-xNaxHx(PO4)2 has a different growth kinetics.