In this paper, we tackle the issue of evaluating an important class of green investing that integrate classical financial tasks with some environmental issues: the so-called green mutual funds. In order to do this, we first propose three measures of environmental sustainability which may give financial agents information on the greenity of their investments. These alternative indicators could serve as an overall measure of environmental sustainability and overcome the drawback that limits the evaluation of green investments to the measurement of CO2 emissions while often more than one environmental aspects may be considered. Secondly, we propose some models aimed at evaluating the performance of green mutual funds by taking into account the proposed environmental measures as well as some classical financial indicators. The analysis is carried out in a Data Envelopment Analysis (DEA) framework, since DEA models can consider strategic non-financial objective measures in addition to traditional financial metrics in order to give a more balanced view of socially responsible investments (SRI). The presented models include indicators of environmental sustainability in different ways, either by penalizing a high environmental consumption or by rewarding an environmental saving entailed by a low consumption. The environmental measures and the models proposed are applied to a set of European green funds in the periods 2012–2015 and 2010–2015 to conduct an extensive analysis. •We propose indicators to measure the environmental saving/consumption of funds.•We evaluate the performance of green mutual funds with a DEA approach.•The DEA models proposed consider both environmental and financial indicators.•An empirical investigation is carried out on European green mutual funds.•A comparison of the performances of green and non-green funds is also conducted.