This thesis aims to empirically study the interlinkages between energy efficiency, environment and productivity at the global level for the period 1993-2013. It contains four main parts: (i) estimating environme ntal energy efficiency (EEE) and analysing its trend across economies over time; (ii) analysing the direction of technical change, its coordination with input mix and its association with EEE at the global level; (iii) elucidating the impact of EEE on total factor productivity; (iv) examining if there has been convergence in EEE among low-, middle- and high-income economies. The empirical results show that global EEE witnessed improvement during the study period except in the years 1998-1999 and 2009. High-income economies have mostly spearheaded this improvement in efficiency followed by the middle-income economies. The low-income economies, on the other hand, have had a near-constant level of EEE over the years. The results also indicated that when the technical change coordinated with the input mix (input biased technical change, IBTC, is greater than unity) for the energy (E) and labour (L) pair, the economies had E-saving/L-using bias in the short-run while majority of the ec onomies had E-using/L-saving bias in the long run at the global level. Moreover, the EEE improvement was observed to be higher when the economies went for E-saving/L-using technical change than when the economies underwent E-using/L-saving technical change. Under the circumstances when IBTC1, economies took up E-using/L-saving technology but used comparatively less energy, experiencing a higher improvement of EEE on the one hand but shrinking of TFP growth on the other hand. Comparing the energy (E) and capital (K) pair, the economies at the global level mostly showed a bias in favour of saving E and using K in the short and long run when IBTC>1 implying that these economies went for mechanization in the production process. EEE improvements were more pronounced when the economies underwent E-saving/K-using technical change than when the economies went for E-using/K-saving technical change. When IBTC1, most of the economies at the global level went for E-saving technology but used relatively more energy than capital, leading to dampening of EEE improvement accompanied by fall in TFP growth. Using panel fixed-effect quantile regression (Powell, 2016), it was found that the relationship between EEE and TFP is non-linear across the entire quantile range of TFP distribution. The results also reveal that the middle-income economies appear to converge to global EEE levels while low-income economies have been lagging behind. Low and high-income economies seem to display club convergence. Hence, EEE at the global level has not shown conditional convergence. Moreover, the technology gap ratio – which captures the closeness of the observed technology of a group of economies’ to the meta-frontier - of middle-income economies are converging towards that of high-income economies whereas low-income economies display a diverging trend especially after the year 2010.