Dataset portals such as Data.gov and Data.uk.gov have become flagship initiatives of open government and open data strategies. These portals aim to fulfill the open government objectives of promoting re-use of public sector information to develop new products and services, and increasing transparency for public officials’ accountability. This work focus on the latter and its aim is to propose a set of requirements as part of a framework to assess whether dataset portals are indeed contributing to a higher degree of transparency focusing on accountability. Previous studies on internet-based transparency (including Internet Financial Reporting – IFR) were analyzed, from which several requirements were derived concerning the data types sought after, the public entities covered, the information seeking strategies adopted and the desired qualitative characteristics of data. The rationale behind our proposal is that dataset portals developed under the open government principles should, at least, be able to fulfill the informational and operational requirements identified in the ‘traditional’ transparency assessment literature.