The preparation of catalysts having molybdate intercalated into a hydrotalcite derived from magnesium aluminium hydroxy carbonate, [Mg6Al2(OH)(16)]CO3.4H2O, has been investigated. The materials produced in a variety of preparations are characterised by elemental analysis, X-ray diffraction pattern, and infrared spectrum. They have been tested as catalysts for the dehydrogenation of propane, both oxidative and non-oxidative. The material, which is most active in oxidative dehydrogenation of propane and the most selective towards propene, was prepared from a calcined commercial hydrotalcite and ammonium dimolybdate with prior impregnation with terephthalic acid and nitric acid. This catalyst had a high molybdenum content (27.3%) and interlayer spacing (10.75 Angstrom). The IR of this catalyst, and the yellow colour, are consistent with a well dispersed magnesium polymolybdate, which is an efficient and selective propane dehydrogenation catalyst.