The dependences of the galvanomagnetic and thermoelectric properties on the thicknesses d (5-200 nm) of PbTe thin films prepared by the thermal evaporation of non-stoichiometric PbTe with 2 at.% excess lead were studied, with measurements conducted in air at room temperature on freshly grown films. It was established that with decreasing film thicknesses, an inversion of the dominant charge carrier sign from n to p takes place at dsimilar to40 nm. A comparison of the results obtained in this work with those for PbTe films prepared from stoichiometric PbTe showed that the increase in n-type charge carrier concentration results in a shift of the inversion point to smaller d values. The observed effect is attributed to oxidation processes taking place in PbTe thin films at room temperature in air, and the effect is interpreted in terms of compensating acceptor states created by oxygen on the film surface.