In aqueous solution, acoustically induced cavitation produces the collapse of bubbles containing gas and water-vapor, producing free radicals by the homolysis of the water molecules. Generally, under these extreme physical conditions, the secondary and tertiary structures of the proteins result are altered and denaturation phenomena are often observed. This paper discusses the evidence that, in the presence of argon and in oxygen-free experimental environment, the reduced horse heart cytochrome c, instead of undergoing a denaturation process, is oxidized to ferric-cytochrome c. Kinetic and circular dichroism measurements performed after ultrasound irradiation at a frequency of 38 kHz are reported. A possible correlation between ultrasound induced molecular damage to the tertiary structure of the proteins and their own extension of helix content is also hypothesized.