Stoichiometric phosphors Li(x)Na(1−x)Sm(PO3)4(x = 0, 0.5, 1) were prepared in the solid state and were characterized at room temperature using X-ray diffraction, infrared and Raman spectroscopy. The obtained LiSm(PO3)4 and NaSm(PO3)4 polycrystalline samples are single-phased and have centrosymmetric monoclinic structure. The observed results show the presence of characteristic bands due to (PO2)− terminal and P−O−P bridging groups. However, the Li0.5Na0.5Sm(PO3)4 material seems to be a mixture of the Li and Na homologues. The VUV excitation and emission spectra of as-synthesized compounds were measured. It was found that the Sm3+ ions show an orange-red emission which corresponds to the group transitions 4G5/2 → 6HJ (J = 5/2, 7/2, 9/2, 11/2), with the strongest transition (4G5/2 → 6H7/2) peaking at around 597 nm. The decay curves were pure exponential. The derived time constants are comprise between 14 μs and 31 μs, the lowest value is for NaSm(PO3)4. The decays were modeled in the frame of fast diffusion model with a rough estimation of fast cross-relaxation mechanism which returns a cross-relaxation rate of 3–7 × 104 s−1 and diffusion constant of 1–2 × 10−9 cm2 s−1.