The project aims at the investigation of pre-ignition phenomena in terms of operation and further development of marine dual-fuel/gas engines. Successful examinations of underlying mechanism based on self-ignition of lube oil will be extended by exhaust gas recirculation and (besides methane as fuel) use of carbon-free ammonia and hydrogen (admixture). In addition to the pre-ignition itself, the influence of the regular ignition process (by reactive jet and/or pilot fuel) is considered. By application of an optically accessible engine test facility with selective lube oil addition, pre-ignition kernels, ignition behaviour, and influence of air/fuel charge and operation conditions shall be investigated. Moreover, mutually approaching flame fronts, and transition from accelerated flame propagation (due to pre-reactions) to knocking events will be examined. The analyzed reference data serves as base for predictive pre-ignition model development.