We conducted optical investigations on the U-1-x,ThxPd2Al3 (0 < x < 0.9) system over a broad frequency range from 15 to 10(5) cm(-1). We evaluated the frequency dependence of the scattering relaxation rate at various temperatures, from which we have characterized the evolution from a Fermi-liquid ground state for x < 0.2 to a non-Fermi-liquid ground state for 0.4 < x < 0.9.