A new method to retrieve thermospheric parameters (Tex, O, O2, N2) from routine foF1 ionosonde observations has been developed and tested using CHAMP/STAR neutral gas density measurements in the European sector. The method was applied to monthly median foF1 data on Rome, Slough/Chilton, and Juliusruh stations to analyze long-term trends in the thermospheric parameters. For the first time the exospheric temperature and neutral composition were obtained for June noontime conditions over the period of  5 solar cycles. The retrieved thermospheric parameter long-term variations were shown to be close to the MSIS-86 model ones exhibiting very small (< 1% per decade) and statistically insignificant linear trends estimated over a 57 year period. No peculiarities in relation with the last deep solar minimum have been revealed. The main conclusion: long-term variations of the thermospheric parameters retrieved in the European region have a natural (not anthropogenic) origin and are mainly controlled by long-term variations of solar and geomagnetic activity.