There is steadily growing interest from energy production and automotive companies in hydrogen as a solution for achieving the goal of net zero emissions. This solution answers the need for a more sustainable energy and mobility model and so using H2 is attracting strong efforts put into making it practical, efficient and cost competitive. Within this framework, the current study proposes a method for implementing 0D/1D simulation for gaining insight into in-cylinder processes during hydrogen fueling of spark ignition engines. A test campaign was implemented on an optically accessible single-cylinder engine operated at 2000 rpm and wide-open throttle (WOT). H2 was delivered in port fuel injection (PFI) configuration, with the duration of injection set at different values that resulted in two relative air-fuel ratio of 2.3 and 2.5. Along with in-cylinder pressure measurements and other thermodynamic parameters, line of sight natural emission spectroscopy was applied in the central region of the combustion chamber, close to the spark plug. The optical data consisted in one spectrum from 280 nm to 420 nm recorded for each engine cycle; as a consequence, the simulation needed to be applied as cycle-to-cycle modeling rather than as averaged traces for each condition. Very good accuracy was achieved in terms of in-cylinder pressure modeling; the simulated concentration of in-cylinder OH at equilibrium was found to be in good agreement with the intensity of the recorded spectra. These results set the basis for implementing more complex chemical kinetics approaches that provide detailed insight into the evolution of species during the working cycle.