(57) A heat-sensitive recording material suited for use in direct thermal imaging and having image-stabilization properties which material contains in a binder on a support (i) a substantially light-insensitive organic silver salt capable of thermally activated reduction to silver in thermal working relationship with (ii) at least one reducing agent capable of reducing the substantially light-insensitive organic silver salt when thermally activated, characterized in that the recording material contains in conjunction, preferably in admixture, with the reducing agent(s) at least one colourless photo-oxidizing substance that on exposure to ultraviolet (UV) radiation, such as present in daylight or artificial lighting, yields free radicals capable of inactivating said reducing agent(s) by oxidation, thereby rendering said reducing agent(s) incapable of reducing said organic silver salt to silver.