Single-phase thin films of the diluted magnetic semiconductor Zn1-xMnxO have been grown by the MOCVD technique. Depositions have been done at T = 450 degrees C on fused silica and (0001) sapphire substrates. Layers on silica exhibit polycrystalline structure with [001] preferential orientation while Zn1-xMnxO films are (0001) epitaxially grown on c-sapphire with the epitaxy relation: 30 degrees rotation of the Zn1-xMnO [100] direction with respect to the [100] of the substrate. The manganese content varies in the (0-30%) range and is always higher in samples grown on sapphire substrates under the same conditions. Variations of a and c lattice parameters, assessed by X-ray diffraction, follow Vegard's law and attest to the incorporation of substitutional Mn2+ ions. Hall effect measurements show a decrease of the mobility with the incorporation of manganese in ZnO, and optical transmission results present the shift of the absorption edge towards higher energies. (c) 2005 Elsevier Ltd. All rights reserved.