Yes / This paper introduces a novel measure of the energy transition, i.e., the green quality of energy mix (GREENQ) across the Organisation for Economic Co-operation and Development (OECD) countries. Then, the paper examines the impact of the GREENQ on CO2 emissions in the panel dataset of 36 OECD countries from 1970 to 2021. The explanatory variables include per capita income, institutional quality and technology. Long-run panel data estimations indicate that per capita income, institutional quality and technology increase CO2 emissions. The novel evidence is that the GREENQ is negatively related to the level of CO2 emissions. These findings are robust to employ different panel data estimation techniques. Potential policy implications are also discussed. / The project was funded by the “Foreign Cultural and Educational Experts Project of the Ministry of Science and Technology of China” (Project Number: DL2022180001L).