A process for saturating a solid material capable of binding ammonia by ad- or absorption and initially free of ammonia or partially saturated with ammonia comprises treating said solid material under a pressure and associated temperature located on the vapor pressure curve of ammonia with an amount of liquid ammonia sufficient to saturate said solid material and an additional amount of a cooling agent selected from liquid ammonia, liquid or solid CO2, hydrocarbons and hydrohalocarbons that have a higher vapour pressure than ammonia, ethyl ether, methyl formate, methyl amine and ethyl amine, such that |Qabs|≦|Qevap|+Qext, wherein Qabs is the amount of heat released from said solid material when it absorbs ammonia from the liquid phase thereof to the point where it is saturated with ammonia, Qevap is the amount of heat absorbed by said cooling agent when it evaporates, and Qext is the amount of heat exchanged with the surroundings and is positive, if heat is removed from the process by external cooling, and negative, if heat is added to the process from the surroundings.