Ultraviolet random lasing action with a tunable wavelength between 375 and 400 nm has been realized from highly disordered Zn1-xMgxO (for 0 <= x <= 0.3) polycrystalline thin films deposited on silicon substrates by the filtered cathodic vacuum arc technique. The emission energy can be continuously tuned within the ranges of 3.10-3.31 eV, while the corresponding lasing threshold remained relatively uniform. (C) 2009 Elsevier B.V. All rights reserved.