The process of recovering precious metals from ores containing precious metals, such as gold and silver, from an aqueous ammoniacal thiosulfate leach solution to provide a significant practical and economical process for the recovery of gold or silver. After leaching of the ore with an aqueous ammoniacal thiosulfate solution, the leach solution is contacted with a precious metal extraction reagent to extract the precious metal values from the leach solution, after which the precious metal values are stripped from the extraction reagent to form a concentrated solution of the precious metal values from which the precious metals may be recovered by conventional methods such as electrolysis. The extraction reagents are those having guanidyl functionality or a quaternary amine functionality mixed with a weak organic acid such as a phenol. In the process, novel thiosulfate complexes of the precious metals are formed with the quanidyl or the quaternary amine extractants.