This deliverable is number 2 of 8 in the project.The current study investigates the impact of fuel reactivity changes caused by the gradual dilution of hydrogen with either methane or carbon monoxide.The impact of nitrogen dilution is also considered.The experimental configuration was chosen to investigate auto-ignition in a turbulent shear layer formed between the fuel jet and a stream of hot combustion products. The results obtained suggest that under the current condition the reactivity of CH4,/H2 blends become increasingly reduced by the CH4 component beyond the 50/50 mixture. By contrast, CO mixtures remain much more reactive over the entire range of conditions. A strong impact of dilution has also been shown and the effect is consistent with a reduced ability of the H2 component of the fuel blend to trigger auto-ignition of thecarbon containing component