Efendiyev Heydar Khalil oglu was born on July 1, 1907 in Sheki city. He graduated from the Faculty of Natural and Mathematical Sciences of the Azerbaijan State University (1931).
In 1941, he received a PhD in Chemistry and a doctor’s in Chemistry in 1958, and in 1959 was a professor of science, and in 1962 elected a corresponding member of the Academy of Sciences of the Azerbaijan SSR.
From 1941 till 1949 he was the head of the laboratory at the Institute of Chemistry of the Academy of Sciences of the Azerbaijan SSR, and since 1949 he was the director of the Institute of Chemistry of the Academy of Sciences of the Azerbaijan SSR.
The main scientific works of H.Afandiyev are devoted to geochemistry of rare-earth elements. He has studied the rare and radioactive distribution patterns of different types of rocks in mineral and petroleum waters of the republic. He developed a new scheme of mineralogy and geochemistry of the hydrothermal ore complex in the north-eastern part of the Lesser Caucasus and led the study of the geochemistry of the new type of colchian-polymetallic deposits found on the southern slopes of the Greater Caucasus (Filizchay, Katex, Katsdag and others).
H. Efendiyev was one of the founders of geochemistry in the republic. He was a good educator, public figure, and science organizer. The geochemistry school he has created is still in operation.
Scientific results obtained by H.Afandiyev are reflected in his work "Radioactivity of mineral waters and rocks of Azerbaijan", "Hydrothermal ore complex of north-eastern part of the Lesser Caucasus", "Introduction to Rare Elements Chemistry", "Geochemistry of Radioactive Elements of Oil Fields" and many others found. H. Efendiyev was the author of 216 scientific works and 8 monographs.
Under his leadership, a doctors of sciences and 15 PhDs have been trained.
H. Afandiyev has invaluable services in the creation and improvement of chemistry and geology terminology in our language.
He was awarded two times with the Order of “Honor” and other medals, the Honorary Decree of the Supreme Soviet of the Azerbaijan SSR.
Corresponding member of ANAS Heydar Afandiyev died in Baku in 1967.