An unfavourable phenomenon is observed: current electronic markets are fragmented and have formed a set of autonomously distributed product information islands. This leads to heterogeneity of product information between separated sources and makes difficult on product document interoperation. To resolve the issue and facilitate business document interoperation, this paper proposes a heterogeneous concept mapping approach. By this approach, heterogeneous product documents are transformed from one context to another context without losing any semantic information. This transformation process is supported by a heterogeneous concept transformation algorithm that includes five transformation steps: source-local context transformation, local-common context transformation, common-common context transformation, common-local context transformation and local-source context transformation.