In e-Business scenarios, an evaluation of the quality of exchanged data is essential for developing service-based applications and correctly performing cooperative activities. Data of low quality can spread all over the cooperative system, but at the same time, improvement can be based on comparing data, correcting them and disseminating high quality data. In this paper, an XML-based broker service for managing data quality in cooperative systems is presented, which selects the best available data from different services. Such a broker also supports data quality improvements based on feedbacks to source services.