Аннотация:In comparative experiments, it was found that the maximum efficiency of third harmonic generation (THG) in cluster nanoplasma was ~9x10-5 and was approximately 4 times less effective than the case of THG in gas under similar experimental conditions. This result is consistent with theoretical calculations and show that THG amplitude in a gas is about an order of magnitude higher than in a cluster medium. The discrepancy between the THG efficiency in gas and clusters obtained theoretically and experimentally in discussed.