The ammonia dissociation reaction is one of a number of reactions which has been investigated for use in closed loop solar thermochemical energy storage systems, over a period of nearly two decades. A recent series of experiments with an electrically heated high pressure ammonia dissociation reactor has validated a two dimensional pseudo-homogenous theoretical reactor model, established rate parameters for the catalyst used, paved the way for a closed loop demonstration and simulated operation of a receiver/ reactor under solar operation. The model has subsequently been used to investigate full sized receiver/ reactor options for a 20 m(2) paraboloidal dish. Technically feasible designs based on: directly irradiated catalyst filled tubes, sodium reflux heat transfer to catalyst tubes and direct absorption of radiation using a windowed pressure vessel, have been identified.