In this study, Li1+xAlxTi2-x(PO4)3 (0.0 ≤ x ≤ 0.5) was prepared by acetic acid-assisted sol-gel method. The structural properties of NASICON phosphates material with chemical formula LiTi2(PO4)3 were observed using the Fourier transform infrared spectroscopy. NASICON is a family of crystalline phosphate with a general network system consisting of PO4 tetrahedra, thus bands were assigned by vibrations contributed by basic phosphates, in the wavenumber region between 1300 cm-1 and 600 cm-1. Experimental spectra indicated that all Li1+xAlxTi2-x(PO4)3 (0.0 ≤ x ≤ 0.5), heat treated at 600°C and 700°C for 3 hours in air, samples showed the presence of phosphate peaks with shift in frequency as Al3+ is substituted into the structure, and with increasing temperatures. Some bands broadened and overlapped causing it hard to analyze the arising bands. It however determined the existence of NASICON structure in all of the samples under study.