Natural Gas/Ammonia (NG/NH 3 ) fuel blends are a promising route to reduce CO 2 emissions from gas turbines while leveraging existing NG infrastructure, but their autoignition behavior at elevated pressures is not yet well constrained. This work reports high-pressure shock tube ignition delay time (IDT) measurements for NG/NH 3 /Air mixtures at gas turbine-relevant conditions. Experiments were performed at pressures of 5, 10, and 25 bar, temperatures from 1500 to 2100 K, with equivalence ratios