He studied Physics at the University of Athens and at the Imperial College London.

Interested in the structure of matter and cosmology, he was engaged in the NESTOR Project, an international scientific collaboration to deploy a neutrino telescope on the sea floor off Pylos.

[1][2] Grammatikakis was a successful author of popular science books on cosmology and physics: Grammatikakis was a member of the board of directors of the former state-owned broadcasting corporation ERT and was vice president of the Greek National Opera.

[3] After a brief hospitalization due to respiratory failure, Grammatikakis died in his hometown, Heraklion, on 25 October 2023, at the age of 84.

[4] His funeral took place on 27 October at the Metropolitan Cathedral of Agios Minas.