The effect of hydrostatic pressure on the ionic conductivities in β-PbF2β-Pb1−xMxmF2+(m−2)x(where Mm= Na+, Cd+2, Tb+3, U+4), LaF3and La1−xCaxF3-xhas been investigated in the temperature range between 300 K and 700 K for pressures up to 0.25 GPa (for β-PbF2) and 0.8 GPa (for LaF3). The activation volumes of defect formation and migration, impurity defect segregation and dissociation were determined from the effect of pressure on the conductivity. Keyes’ treatment based on the strain energy Zener model in Grüenisen approximation was used to estimate theoretical values of activation volumes.