The γ-ray densitometer has been designed and fabricated in our laboratory and carried out studies on temperature dependent γ-ray attenuation and thermo physical properties of NaCl, NaBr and NaF. The linear attenuation coefficients (μl) for the pellets of NaCl, NaBr and NaF as a function of temperature have been determined. The coefficients of temperature dependence of density have been reported. The variation of density and thermal expansion of NaCl, NaBr and NaF in the temperature range of 300 K - 1000 K have been studied and compared with results available in the literature. The temperature dependence of density and thermal expansion has been represented by linear equations. Volume thermal expansion coefficients have been reported.