In 1959 - graduated from Dnepropetrovsk Chemical-Technological Institute to be engineer-mechanic.
In 1968 - graduated from Irkutsk Polytechnical Institute to be a specialist on oil and gas.
During 40 years of working activity on an oil-refining enterprise Demjanenco rose from an operator to a shop head.
In 1971-83 - head of the building Achinsk oil-refining plant.
Since 1983 - head of the plant.