Novel thermochemical energy storage systems that employ fluidized beds of CaO/Ca(OH)(2) for hydration/dehydration reactions are under development because of the inherent advantages of the low cost of the materials and their relatively high temperature operation-windows (450 degrees C-550 degrees C). We report in this work the results of the first steady state experiments conducted in a new pilot plant designed to test the concept under realistic reactor conditions. The pilot has a fluidized bed reactor with an internal diameter of 0.108 m and a height of 780 mm fed continuously with gas and solids as well as heat exchangers to supply/extract the required reaction heat. The experimental results during dynamic and steady state periods were fitted to a KL reactor bubbling bed model, using kinetic parameters from thermogravimetric studies and a single crossflow factor. The resulting continuous reactor model will serve as useful tool for the continued scaling up of this technology.