The influence of low concentration (1 mol%) Mg doping on the structural, microstructural, surface morphological and dielectric properties of Ba1-xSrxTiO3 thin films has been measured and analyzed. The films were fabricated on MgO and Pt-Si substrates via the metalorganic solution deposition technique using carboxylate-alkoxide precursors and post deposition annealed at 800 °C (film/MgO substrates) and 750 °C (film/Pt-Si substrates). The structure, microstructure, surface morphology and film/substrate compositional quality were analyzed and correlated to the films dielectric and insulating properties. Dielectric properties of unpatterned films were measured at 10 GHz with a coupled/split dielectric resonator system and at 100 kHz using metal-insulator-metal capacitors. The Mg-doped BST films exhibited improved dielectric loss and insulating characteristics compared to the undoped Ba0.6Sr0.4TiO3 thin films. The improved dielectric properties, low leakage current, and good tunability of the low level Mgdoped BST thin films merit strong potential for utilization in microwave tunable devices.