In this paper, we present COCALEREX (converting relational to XML) which can address both catalog-based and legacy relational databases. It handles the latter category by first applying the reverse engineering approach described in [2] to extract the ER (Extended Entity Relationship) model from legacy relational databases. This reverse engineering approach is emplyed also not to extract from catalog-based databases meta-data not available in the catalog. Then, COCALEREX converts the ER to XML schema. Deriving the ER model empowers the proposed approach to smoothly consider many-to-many and nary relationships during the mapping into XML schema. COCALEREX provides a user-friendly interface that displays the result of each phase of the conversion process. Experimental results are encouraging, demonstrating the applicability and effectiveness of the proposed approach.