University of Guilan Caspian Journal of Environmental Sciences 1735-3033 24 3 2026 07 01 Green transition, institutions and environmental efficiency in OECD economies 837 864 9797 10.22124/cjes.2026.9797 EN Azizbek Khurramov International School of Finance Technology and Science, Tashkent, Uzbekistan Anvar Avlokulov Tashkent State University of Economics, Tashkent, Uzbekistan Otaxon Qushmatov Tashkent State University of Economics, Tashkent, Uzbekistan Muxammadi Xayitboyev Tashkent State University of Economics, Tashkent, Uzbekistan Sanjar B. Bobokulov Samarkand Institute of Economics and Service, 140100 Samarkand, Uzbekistan Nargiza SH. Abdieva Tashkent State University of Economics, Tashkent, Uzbekistan Sitorabonu Abdiganiyeva International School of Finance Technology and Science, Tashkent, Uzbekistan Saodat T. Toshalieva Termez State University, Termez, Uzbekistan Umida Khalikova Bukhara State University, Bukhara, Uzbekistan Fakhriddin KH. Karimov Tashkent State University of Economics, Tashkent, Uzbekistan Dilfuza T. Yakubova International School of Finance Technology and Science, Tashkent, Uzbekistan Abduraimov Bunet Campus of the University of Economics and Pedagogy, Samarkand, Uzbekistan Layli S. Mirzayeva Tashkent State University of Economics, Tashkent, Uzbekistan Journal Article 2026 07 30 The green transition is frequently framed as a primarily technological undertaking, yet its environmental payoff depends on the institutional and structural conditions under which clean-energy and innovation inputs are deployed. This paper develops an integrated green-transition and institutional–environmental-efficiency framework and tests it on an unbalanced panel of 38 OECD economies observed between 2000 and 2021. We distinguish two complementary outcomes-  emissions per capita, which capture environmental pressure, and energy intensity, which captures environmental efficiency-and estimate their determinants with two-way fixed-effects models corrected by Driscoll–Kraay standard errors that are robust to heteroskedasticity, serial correlation and cross-sectional dependence. The empirical strategy layers a baseline specification with an Environmental Kuznets Curve test on mean-centred income, institutional interaction models, a panel quantile analysis of distributional heterogeneity, and robustness checks using logistics performance and the individual governance indicators. Renewable energy consistently and significantly lowers  emissions across all specifications, whereas research and development, income and institutional quality operate more visibly through the energy-efficiency channel. The central contribution is evidence that institutional quality, though not a simple linear depressant of emissions, strengthens the environmental effectiveness of both renewable energy and innovation: all four institution-by-input interactions are negative and statistically significant. The findings portray the OECD green transition as jointly technological, structural and institutional, and imply that governance capacity should be treated as a multiplier that converts green-transition inputs into measurable environmental performance. https://cjes.guilan.ac.ir/article_9797_53df81a3b1f0bc09fc2ac9a81fdcd6f0.pdf