The paper presents experimental results of the interaction of thin layers (83 and 310 nm) of lead phthalocyanine (PbPc) with trace amounts of toxic gas NO2 in a system with an acoustic surface wave on a LiNbO3 Y-Z substrate. PbPc films were prepared according to the usual vacuum evaporation method. Measurements of the sensor properties rely on changes in the differential frequency, deltaf, of the dual-delay line configuration, in one of which the investigated PbPc layer has been placed. Special stress has been put on the temperature dependence of the reversibility in the medium range, i.e. between 27 degrees C and 95 degrees C. Besides, one simple method for thin PbPc film regeneration in a low NO2 concentration range has been presented.