A non-intrusive method for monitoring hydrocarbons, gas and oil flames, is introduced in this paper. The method is based in a radiometry measurement of the flame, which is implemented by using an array of silicon photodiodes with interference optical filters. The array is designed to cover wavelengths for evaluating the formation and behaviour of excited CH* and C-2* radicals. These radicals CH and C-2* can be detected at centre wavelengths of 432nm and 516nm respectively. The radiometry analysis for monitoring non-confined oil flames was checked by a radiometer, using crosscorrelation data. These radicals are also measured for gas flames in the reaction region for a confined flame. Simple and low cost electronic was designed to drive the array of silicon photodiodes and they were set in an optical system and in a data acquisition system. The tests reported demonstrate that the flame condition can be adequately monitored for different air excess, different axial position as well as for different firing rate. Indeed, experimental test were taken for two power level: low and high firing rate. The fast response, the non-intrusive character and the instantaneous measurement of information make the proposed optical sensor a key to develop advances control strategies, which can be used successfully in combustion processes.