The influence of sulphur incorporation during electrodeposition on the structural and magnetic properties of both Co and Co-Ag thin films from aqueous thiosulphate solutions has been investigated. Co-Ag deposits containing sulphur showed granular morphology and varying cobalt and sulphur contents as a function of the applied potential. Nanocrystalline soft-magnetic deposits whose coercivity decreased as sulphur incorporation increased were obtained. More influence of the sulphur presence on the cobalt thin film magnetic properties was observed due to the significant structural changes induced by sulphur incorporation into the crystalline lattice. When high amounts of S were present, soft-magnetic amorphous cobalt coatings were obtained. On the other hand, stronger hard-magnetic behaviour was detected on those crystalline thin films where S content was lesser. (C) 2010 Elsevier B.V. All rights reserved.