Abstract: A process for the treatment of a material which is or is suspected to contain or carry one or more actinides or compounds thereof to dissolve such actinides or compounds comprises contacting the material with an aqueous solution having a pH in the range 5.5 to 10.5 which is free of heavy metal ions and comprises ingredients which are naturally degradable to non-toxic products with or without mild physical assistance such as heat or ultra-violet radiation, said solution comprising:(a) carbonated water;(b) a conditioning agent;and (c) a complexing agent which comprises the anion of a carboxylic acid having from 2 to 6 carbon atoms.The process may be employed to separate spent nuclear fuel from its metal containment or it may be employed to decontaminate surface, e.g. concrete or soil or pipes carrying traces of actinides, or bulk materials such as soil or rubble.