Sándor Jemnitz, also known as Alexander Jemnitz (9 August 1890 in Budapest – 8 August 1963 in Balatonföldvár), was a Hungarian composer, conductor, music critic and author.
Jemnitz studied composition with János Koessler at the Budapest Music Academy from 1906 to 1908, then continued his studies at the Leipzig Conservatory where he studied organ with Karl Straube, violin with Hans Sitt, composition with Max Reger, and conducting with Arthur Nikisch. From 1913 to 1915 Jemnitz lived in Berlin and studied composition with Arnold Schoenberg and began writing articles on music, several of which were published in Die Musik in 1914 and 1915.
Jemnitz returned to Hungary in 1916 and wrote for various newspapers and periodicals. From 1924 to 1950 he was regular music critic of the Népszava newspaper, in which post he established himself as one of the most respected Hungarian critics of the period. Jemnitz taught at the Béla Bartók Conservatory of Music in Budapest from 1951. During his last years, he published several popular books on composers including Felix Mendelssohn, Frédéric Chopin and Wolfgang Amadeus Mozart.
Jemnitz's musical style is heavily influenced by Reger and Schoenberg. His compositions include works for orchestra and keyboard, as well as vocal, choral and chamber music.