A novel in-cylinder diagnostic technique for time-resolved investigation of intermediate combustion products during the combustion of one engine cycle is discussed. UV/VIS emission spectra are recorded from inside the combustion chamber with temporal resolution in the μs-range. By means of a spark light-conducting sensor the investigations are applied to production engines. The special arrangement and the setup of the high seep detecting system, a modified CCD-camera with a streak-mode operation, are discribed. The general design concept is outlined and first experimental results are presented.Experimental results were obtained both on a SI engine and a diesel engine. The results are plotted as 3-d-images with time and wavelength and the intensity as colored 3rd dimension. They are time-resolved for the complete or a chosen part of the combustion cycle. The highly resolved spectral and temporal images are used to chart the progress of the combustion by observing the emissions of intermediate combustion products, molecule formation processes or particle emissions. This high speed investigation may yield helpful information for the improvements of engine design and control.