LaPO4 nanophosphors doped with Tb3+ were synthesized using a simple co-precipitation method in deionized water with NH4H2PO4 and La(NO3).5H2O using Tb(NO3) as the dopant at various pH values while maintaining a constant concentration. X-ray diffraction studies indicate a decrease in particle size with an increase in pH beyond pH 4. Photoluminescence (PL) studies reveal that PL intensity increases with rising pH and then decreases, likely due to changes in crystallinity. SEM and TEM images show that the synthesized nanoparticles have a nanorod structure. FTIR and EDX analyses were also conducted to determine the elemental composition of the nanoparticles.