Brazil's power sector reforms are encouraging private investments in the expansion of installed power capacity. Also, natural gas fired thermopower technologies are becoming increasingly important, as they offer faster returns on investment. However. a series of institutional and tariff barriers still block implementation of gas fired cogeneration projects, which are concentrated mainly in the industrial sector. For the commercial sector, despite its relative heterogeneity from the standpoint of both size as well as purpose. cogeneration projects have the advantage of being relatively simple. This article identifies the technical and economic potential of natural gas fired cogeneration systems for malls in Rio de Janeiro through the use of an assessment model. The results are unfavorable within the current regulatory and tariff context in Brazil, indicating the need for combined policies to provide incentives for cogeneration projects in the Brazilian commercial sector. (C) 2000 Elsevier Science Ltd. All rights reserved.