The data collated here are the results of tests carried out to model at reduced scale, the consequences of a flameout in a full-size combined cycle gas turbine (CCGT) when running on high hydrogen fuel mixtures. In December 2019 the Phase 2 data and supporting documents were added. Earlier results and documentation were not changed. README files were updated accordingly. The data were produced during laboratory and reduced scale tests using a cylindrical duct and a reduced-scale model of a combined cycle gas turbine (CCGT) complete with a model heat recovery steam generator (HRSG). These facilities provided a means of measuring the consequences of ignitions of hydrogen and flammable gas mixtures, in this case binary mixtures consisting of hydrogen/methane or hydrogen/carbon monoxide, when they are injected and spark ignited in the hot exhaust stream from a gas turbine. The overall intention of the work was to provide data sets that could be used to aid understanding of the physical processes involved as well as providing data that could be used for CFD modelling of the whole process. Use of these data are subject to the High Hydrogen Project ETI Open Licence for Materials. Make sure you read the terms and conditions at http://data.ukedc.rl.ac.uk/simplebrowse/edc/hydrogen/h2/High_Hydrogen/High_Hydrogen_Project_ETI_Open_Licence.txt