A method is described for preparing an eggshell catalyst comprising the steps of: (i) preparing a calcined shaped alkaline earth metal aluminate catalyst support, (ii) treating the calcined shaped alkaline earth metal aluminate support with a gas containing water vapour to form a hydrated support, (iii) with or without an intervening drying step, impregnating the hydrated support with an acidic solution containing one or more catalytic metal compounds and drying the impregnated support, (iv) calcining the dried impregnated support, to form a calcined catalyst having a catalytic metal oxide concentrated at the surface of the support and (v) optionally repeating steps (ii), (iii) and (iv).