[3] Ossovsky maintained close ties with the composers of Belyayev's Circle and had become friend and colleague with a number of the members of Russian musical elite, including Sergei Rachmaninoff, Alexander Siloti and Alexander Glazunov.
The same year, in Kyiv, Rachmaninoff at the request of Ossovsky auditioned Ossovsky's cousin, Ksenia Derzhinskaia (1889–1951),[5] and helped to launch her opera career; she became an eminent Russian singer and prima donna at the Bolshoi Theatre in Moscow.
He had written a series of papers and monographs dedicated to research and analysis of the works of such outstanding Russian composers as Mikhail Glinka, Glazunov, Rimsky-Korsakov and others.
He was one of the first musicologists who introduced music of Bach, Rameau, Corelli, Vivaldi and Wagner to the Russian public.
[8][9] Ossovsky's works are frequently cited in many Western publications about Russian composers and their music.