In the present work the temperature dependences of strontium-praseodymium oxysilicate heat capacity have been measured for the first time in the range from 4.7 to 347 K by precision adiabatic vacuum calorimetry. The experimental data were used to calculate standard thermodynamic functions, namely the heat capacity Cp degrees(T), enthalpy H degrees(T) - H (0), entropy S degrees(T) - S degrees(0) and Gibbs function G degrees(T) - H degrees(0), for the range from T -> 0 to 347 K. Thermal expansion coefficients of the SrPr4(SiO4)(3)O crystal structure were calculated using in situ thermoroentgenography (alpha(a) = 10.0 . 10(-6) K-1; alpha(c) = 6.7 . 10(-6) K-1; alpha(v) = 26.9 . 10(-6) K-1). On the basis of features of thermal expansion ion conductivity mechanism in apatites was explained. (C) 2017 Elsevier Ltd.