The reaction of molybdenum trioxide dihydrate, MoO3·2H2O, with methanol produces the title compounds. That these molybdenum oxy-methoxides decompose with liberation of CH2O suggests that they represent exquisite models for selective oxidation of methanol to formaldehyde over molybdate catalysts. While a number of physical techniques have been employed to elucidate certain of their structural aspects, unfortunately, the detailed structures of these materials remain unknown. Problems, both physical and crystallographic, encountered in attempts to determine these structures are discussed. Also discussed is the recent progress made by employing the complimentary nature of electron and powder diffraction techniques.