Career
Born as Cosmé McMunn in Mapimí, Mexico in 1901, he moved with his family to San Antonio, Texas around 1911. He moved to New York City around 1920 to further his musical studies, and likely adopted the McMoon surname around that time. Jenkins met McMoon in the late 1920s, and knowing McMoon was a concert pianist, eventually asked him to help her prepare for her performances and accompany her.
McMoon resided in New York City until shortly before his death in August 1980.
He was diagnosed with pancreatic cancer and moved to San Antonio, Texas. He was buried in San Antonio.
McMoon was portrayed by actor Donald Corren in Souvenir, a play about Florence Foster Jenkins" career, which ran on Broadway in 2004 and has since been staged in many regional theaters. He will be portrayed by Simon Helberg in the upcoming feature-film about the life of Jenkins titled Florence Foster Jenkins.