V. SUMMARY In this paper a fibre optic pressure and temperature sensor for down-hole applications has been successfully tested. An experimental set up was developed in order to evaluate the fibre optic sensor under in-situ pressure and temperature conditions. Experimental results illustrate that the developed fibre optic sensor can measure pressure and temperature at the point of measurement. The application at higher temperatures will be tested and the long term stability will be evaluated. Improvements of the interrogation system and signal processing are currently under investigation to enhance the pressure and temperature resolution.