Leonid Kadenyuk was born on 28 January 1951 in the village of Klishkivtsi in the Khotyn Raion of the Chernivtsi Oblast in Ukraine, to a family of rural teachers.

Between 1988 and 1990 he underwent engineering and flight training in the Buran program as commander of the planned Soviet reusable spacecraft.

With the break-up of the Soviet Union, Kadenyuk remained in the Russian Space Forces and adopted Ukrainian citizenship.

Preparing for space flight, from April to October 1996 he worked as a researcher at the Department of Phytohormonology of the Kholodny Institute of Botany of the National Academy of Sciences of Ukraine.

He was trained to conduct scientific experiments on board spacecraft in various fields: biology, medicine, metrology, ecology, study of natural resources of the Earth from space, geology, astronomy, geobotany.

In the laboratory module "Spacelab" scientific experiments in the fields of astrobiology, physics and materials science were carried out, astronauts were also scheduled to go into outer space.

During his flight with shuttle Columbia, he performed biological experiments of a joint Ukrainian-American scientific study with three species of plants: turnip, soybean and moss.

The main purpose of the experiments was to study the effect of weightlessness on the photosynthetic apparatus of plants, on fertilization and embryo development, on gene expression in soybean and turnip tissues, on the content of phytohormones in turnip plants, on hydrocarbon metabolism and ultrastructure of soybean sprout cells.

From the astronaut's memoirs: "7 days before the launch, a special regime was introduced for our crew in order to prevent infectious diseases – quarantine.

Therefore, Leonid Kostyantynovych ordered it to signal the awakening of the crew, which was broadcast from the Flight Control Center on board the "Columbia".

3 in the electoral party list of Lytvyn's People's Bloc, but the block won only 2.44% of the popular vote (short of the required 3%) and no seats in the parliament.

On 19 January 1998, Kadenyuk received the Order "For Courage" I degree of the Distinction of the President of Ukraine for outstanding contribution to the international prestige of the national space industry and personal courage and heroism shown during the Ukrainian-American scientific research aboard the Space Shuttle Columbia.

Order "For Merits" III st. – for significant personal contribution to the development of the rocket and space industry, significant achievements in the creation and implementation of space systems and technologies, high professionalism (12 April 2011)In 2004, astronomers at Andrushivka Astronomical Observatory named Asteroid 399673 Kadenyuk in his honor.

On April 4, 2020, sculptor Valentyn Znoba created a bas-relief portrait of Kadenyuk for the National Technical University of Ukraine.