Full text can be accessed at http://onlinelibrary.wiley.com/doi/10.1002/pssa.200521146/fullSuperconducting thin films of MgB2 were grown in situ by co-evaporation of magnesium and boron on MgO (111), SiC (0001) and Al2O3 (0001) substrates at ∼300 °C. The films showed transitions to the superconducting state in the temperature range of 33–37 K. The widths of the superconducting transitions were less than 1 K. The films exhibited growth in the c-axis and absence of other phases. Optimization of the growth parameters enabled films with smooth surface morphology and root-mean-square (RMS) roughness of 2 nm to be grown. The low RMS roughness value indicates that the technique can be used to grow MgB2 films useful for junctions and multilayer devices. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)