Abstract This study describes the models employed, the main scenario constraints and the energy and climate policy assumptions for a companion study on “European decarbonisation pathways under alternative technological and policy choices: A multi-model analysis”. We describe the main characteristics, the coverage and applications of seven large-scale energy-economy EU models used in the aforementioned study (PRIMES, GEM-E3, TIMES-PanEu, NEMESIS, WorldScan, Green-X and GAINS). The alternative scenarios modelled and the underlying assumptions and constraints are also specified. The main European energy and climate policies assumed to be implemented in the Reference scenario are outlined. We explain the formula used for the decomposition of carbon emissions reduction achieved in the basic decarbonisation scenario relative to the reference. Detailed model results for the power generation mix and RES deployment in the basic decarbonisation scenario in the EU are also presented. We conclude the description of our modelling approach with a brief comparison of the strengths and weaknesses of the models used.