The present work aims to study a rectangular single-element combustion chamber performances by using methane and oxygen as propellants. Sensors were applied to the combustion chamber to detect useful parameters, in order to calculate performance indicies of rocket through a MATLAB code. Furthermore, an optical window is present to allow an ICCD Camera to take pictures of flame to investigate the flame emissions: this is a non-intrusive optical diagnostic technique which takes the name of Chemiluminescence Imaging. The camera sensor used is covered by an optical filter which makes radicals OH^* visible. From data collected by camera, it is possible to deduce how OH^* concentration affects changes in brightness and hence how the mixing evolves in different cases.