Powder phosphor yttrium aluminum garnet (YAG), doped with trivalent cerium (Ce3+), is synthesized by using the solid state reaction method. The formation of YAG and YAG:Ce (cerium-doped yttrium aluminum garnet) was investigated by means of X-ray diffraction (XRD) which shows that the powder is a single phase constituted of grains with sizes of about 70 nm. From the photoluminescence spectra, it was confirmed that the synthesized YAG:Ce3+ phosphor emits typical yellow light peaked at around 550 nm under an excitation of 473 nm-wavelength. By using the Photo-Thermal Deflection (PTD) technique, heat transfer modes are studied and, thermal conductivity, thermal diffusivity, specific heat and mean free path are determined and obtained respectively in the order of 12 W m(-1) K-1, 2 m(2) s(-1), 800 J mol(-1) and 7.5 angstrom, which are in good agreement with literature.