Niobium coatings (6-8 mu m thickness) were deposited on 316L stainless steel substrates using the physical vapour deposition technique of magnetron sputtering at selected argon gas pressures, varying from 0.14 to 3.0 Pa. This paper examines the structure, adhesion and hardness of Nb coatings deposited under such conditions. Structural characterisation (morphology and crystallography) was assessed using scanning electron microscopy and reflection high-energy electron diffraction. The adhesion of Nb coatings, determined by the scratch test method, showed dependence on changes in argon gas pressure used in the deposition process. Three mechanisms, coating cracking, coating lifting and finally, coating removal, characterising the loss of film to substrate adhesion were identified. It was possible to correlate the pressure dependence of the adhesion of Nb coatings with the accompanying morphological changes. In contrast, the hardness properties of the coatings remained largely invariant of the deposition gas pressure in the range investigated.