Heydar Haji Najaf oghlu Huseynov was born on April 3, 1908 in the Tepebashi district of Iravan in the family of a merchant Haji Najaf Karbalayi Huseynov and Mashadi Gulsum. He was the youngest of the six children. Soon after Heydar was born, his father died. After his elder brother Yusif was killed by Armenian gangs in 1918, his family first moved to Batum, then to Stavropol, and in 1920 to Baku. Heydar Huseynov grew up under the protection of his older brother and mother.

Heydar Huseynov continued his education at school number 18 in Baku. After graduating from the Azerbaijan State University in 1931, he worked in various fields: a teacher in a secondary school, a researcher at the Azerbaijan Encyclopedia Publishing Committee (1936), a scientific secretary (1937). In 1938, H.Huseynov was appointed director of the Institute of Encyclopedias and Dictionaries. During this period, his book “Philosophical Views of M.F. Akhundov” was published.

1939 was a successful year for the scientist. In that year, he defended his thesis dedicated to the philosophical heritage of M.F.Akhundov at the scientific council of Tbilisi University and received the degree of candidate in philosophy. The books “Dialectical Materialism”, “Dialectics and Metaphysics”, “Russian-Azerbaijani Dictionary” were published. He was also elected an associate professor of the “Dialectical and historical materialism” department.

In 1940, H.Huseynov was awarded the Order of Honor. At that time, he was the vice-chairman of the USSR Academy of Sciences’ Azerbaijani branch, and from 1944, he was the chairman. In 1944, the distinguished philosopher, who received the scientific title of Doctor of Philosophy, became one of the first full members of the Azerbaijan Academy of Sciences a year later. During these years, the prolific scientist’s books “Akhundov’s Philosophical Views” (1942), “Patriotic Poet Samad Vurghun” (1942), “Azerbaijani Intellectuals in the Days of the Patriotic War” (1944), “Literary Notes” (1945) and others were published. He was also one of the editors of the history of “Comprehensive Azerbaijani literature” (volumes 1-2; 1943–1944).

During this period, the highest peak of H.Huseynov’s creativity was the book “Russian-Azerbaijani Complete Dictionary” (1940–1946), which he compiled together with M. Mirbabayev and A. Orujov. In 1943, before the 4th volume of the dictionary was published, academician I. Meshshaninov called it “the largest among Russian national dictionaries” and highly appreciated the work of Azerbaijani scientists. For this work, he was awarded the title of recipient of the “Stalin” prize (later the State Prize of the USSR).

H.Huseynov published the books “Nizami’s Public Views” in 1946, “Prominent Azerbaijani Scientist A.A. Bakikhanov” in 1950, and ” On the History of Social and Philosophical Thought in Azerbaijan in the 19th Century “.

Despite the awarding of Heydar Huseynov’s scientific activity, the republic’s leadership began to show intolerance towards him. In May 1950, his book “On the History of Social and Philosophical Thought in Azerbaijan in the 19th Century” was severely criticized at the bureau meeting of the Central Committee of the Communist Party of Azerbaijan in May 1950. He was accused of promoting Muridism and glorifying Sufism, and was deprived of the State Prize. Academician H.Huseynov, who did not tolerate persecution and insults, committed suicide on August 15, 1950.

The outstanding scientist held four major positions for many years. He was the vice-president of the Academy of Sciences of the Azerbaijan SSR, the head of the social sciences department of the academy, the head of the philosophy department of Azerbaijan State University, and the director of the Azerbaijan Institute of Party History, as well as a deputy of the Supreme Soviet of the Azerbaijan SSR and the Baku City Soviet of Workers’ Deputies.

In 2008, the 100th anniversary of academician Heydar Huseynov was celebrated at a high level across the republic.