High-pressure electrical conductivity measurements and differential thermal analysis have been carried out on poly(propylene glycol) (PPG) complexed with LiCF3SO3 (composition O:Li=20:1) for pressures up to 1 GPa. The temperature and pressure dependence of the conductivity were analyzed in terms of the recently presented generalized Vogel equation as well as the well-known Vogel–Tamman–Fulcher equation, and the former provides an improved description of the data. The conductivity results show that the apparent activation volumes for the conduction process at room temperature and atmospheric pressure are 48 and 42 cm3 mol−1 for electrolyte based on PPG4000 (molecular weight=4000) and PPG400, respectively. The temperature variation of the activation volume as well as the molecular weight dependence are described well within the free volume theory, which also provide a reasonable description of the pressure dependence. Differential thermal analysis was used to determine the pressure dependence of the glass transition temperature T g for the electrolyte based on PPG400. The result for the initial slope dT g/dp=140 K GPa−1 agrees well with that for the pure host PPG, but T g is shifted up 6 K.