The interface reactions in Co/W multilayers (ML) with Co thickness of 1 and 2 nm and W thickness of 1, 2 and 5 nm in as deposited state and under KrF laser irradiation with fluences F = 50-200 mJ/cm(2) were studied by different X-ray methods. Superlattice satellites around W (1 1 0) direction were found in as-deposited and irradiated multilayers. The layered structure persists up to the highest applied fluence. Co3W compound is formed at the interfaces. However, the intermixing is low. (C) 2002 Elsevier Science B.V. All rights reserved.