Electronic marketplaces are virtual communities where buyers may meet proposals of several suppliers and make the best choice. The exponential increment of the e-commerce amplifies the proliferation of different standards and joint initiatives for the classification of products and services. Therefore, B2B and B2C marketplaces have to classify products and goods according to different product classification standards. In this paper, we propose a framework to classify and reclassify electronic catalogs based on a semi-automatic methodology to define semantic mappings among different product classification standards and catalogs. Categories and Subject Descriptors H.2.5 [Database Management]: Heterogeneous Databases Data translation. Keywords Semantic mappings, Product classification standards, Electronics Catalogs, Annotations, Catalog Reclassification