An intermediate in the ethanolysis reactions of MoCl5, [MoOCl3(EtOH)] (2), was isolated after the reaction of MoCl5 with 2 equiv of EtOH and its crystal structure was detd. Treatment of MoCl5 with 2.5 equiv of EtOH and subsequent cooling as well as the reaction of [Cl2OMo(m-OEt)2(m-HOEt)MoOCl2] (1) with HCl(g) yield a product which was identified as H[MoOCl4].2EtOH 3 by x-ray crystallog. The mechanisms leading to 1-3 are discussed. The reactions of 2 with donors were studied and [Cl2OMo(m-OPr)2(m-HOPr)MoOCl2] (4) was obtained as a 1st deriv. of 1 after the reaction of MoCl5 with PrOH.