Adsorption heat exchanger devices (11, 30) are provided for solid sorption refrigeration systems (1). Such a device includes a heat exchanger (12) having a plurality of projections (17) arranged for extending into an adsorbate of the system (1) in use. An adsorption structure (13, 31) is formed on the heat exchanger (12) for adsorption of said adsorbate. The adsorption structure (13, 31) comprises a plurality of elongate adsorption elements (20) extending outwardly from each of said projections (17) of the heat exchanger (12).