Na + -conducting sodium dysprosium (phospho) silicates with the compositions Na 5 DySi 4 O 12 , Na 3.9 Dy 0.6 P 0.3 Si 2.7 O 9 and Na 3.9 Dy 0.6 Si 3 O 8.85 were synthesized by solid state route. The phase evolution in the three systems was studied as a function of heat treatment temperature from 600°C to 1000°C by X-ray diffraction technique. It was possible to achieve a NASICON Na 5 DySi 4 O 12 -type single phase with the compositions Na 3.9 Dy 0.6 P 0.3 Si 2.7 O 9 and Na 3.9 Dy 0.6 Si 3 O 8.85 at 800°C. Heat treatment at a higher temperature (>850°C) resulted in the formation of a less conductive Na 9 DySi 6 O 18 -type phase. Conventional and microwave sintering were carried out on Na 3.9 Dy 0.6 P 0.3 Si 2.7 O 9 sample at 800°C and the ionic conductivities were measured as a function of temperature from 75°C to 325°C. The microwave sintered sample exhibited better Na + ionic conductivity of 0.42×10 −2 S/cm when compared to that of conventionally sintered sample which was 0.43×10 −3 S/cm at 325°C.