In 1954 he defended his doctoral dissertation, titled Drevnevostochnye materialy po istorii narodov Zakavkazya (Materials from the Ancient East on the history of the peoples of the Transcaucasus).
Through his study of Urartian cuneiform inscriptions, he addressed questions of the historical geography and population groups of the ancient Near East.
He focused on the social and economic features of Nairi-Urartu and studied the culture and religious beliefs of its peoples.
In Urartskie klinoobraznye nadpisi, he collected all Urartian inscriptions known at the time, with transliterations, translations, and commentary on the texts.
Some of Melikishvili's most influential essays were published in 1999 in the collection Dziebani sakartvelos, k'avk'asiisa da akhlo aghmosavletis dzveli ist'oriis dargshi (Researches in the ancient history of Georgia, Caucasia and the Near East).