Environmental issues have posed major challenge in terms of social and environmental responsibility and even reference to their identification, recognition, measurement and disclosure by the accounting. The issue involves judgment and expertise from different areas of knowledge, particularly the accounting that seeks to provide useful information for the decision-making process. This research aims to identify how it can happen to disclosure in public institutions, seeking to improve their accountability regarding the environmental impacts resulting of its economic activities. Literature analyzed extracted a framework for environmental information to be highlighted and that will produce outcomes could be compared, as announced in the study by Gray et al (1995). The empirical analysis was carried out in the municipality of Belo Horizonte, responsible for most of the "ICMS Ecológico" of Minas Gerais state. Were analyzed the available accounting reports in official website "Portal da Transparência" and, from a content analysis, scores were assigned to the disclosures found, according to the theoretical consulted. The results show that in 2010, compared to 2009, the city improved its level of disclosure, however, did not reach more than 13% of the maximum score assigned according to the criteria of disclosure in this study.