In 1993, Nikitenko defended her candidate's thesis Historical problems in the frescoes of Sophia of Kyiv (Institute of Universal History of the Russian Academy of Sciences, Moscow, scientific supervisor, Academician of the Russian Academy of Sciences Gennadii Lytavrin), and in 2002 - a doctoral dissertation Rus-Ukraine and Byzantium in the monumental complex of Sophia of Kyiv: historical, social and ethnic-confessional aspects (Institute of Ukrainian Archeography and Source Studies named after Mykhailo Hrushevsky, National Academy of Sciences of Ukraine, Kyiv).

She discovered and comprehensively substantiated the fact of the emergence of Sophia in 1011-1018, at the end of the reigns of the baptizer of Russia Volodymyr the Great and his son Yaroslav the Wise.

In September 2011, according to the decision of the 35th session of the UNESCO General Conference (October 2009) and according to the Decree of the President of Ukraine dated June 11, 2010, the 1000th anniversary of the founding of Sophia of Kyiv was solemnly celebrated at the international and national levels.

[5] For the first time, Nikitenko put forward and substantiated the hypothesis about the 1000th anniversary of the Golden Gate with the gateway church and defensive earthen rampart, which arose simultaneously with Sophia of Kyiv as integral parts of a single urban planning complex, conceived and started by Volodymyr and completed by Yaroslav.

In June 2012, Nikitenko was forced to temporarily leave the Sophia Nature Reserve due to the repressive actions of its new management.