In parallel to the study and teaching of Ancient Greek and European Philosophy (Medieval - Modern) at an undergraduate and postgraduate level, K. Th. Petsios has oriented his academic interests towards research into the manuscript Modern Greek philosophical tradition. Nearly all his earlier and more recent studies make use of unknown and, in many cases, undocumented sources. Through a process of hermeneutic reconstruction of the evidence, he has attempted to shape the theoretical framework within which one can inscribe the philosophical connections between Ancient Greek, European (Medieval and Modern) and Modern Greek (from the 15^th to the 20^th century) thought. He has also contributed to that end through the editions of philosophical manuscripts, which include texts by Nikephoros Klarontsanos (†1645), Nikolaos Koursoulas (1602-1652), Gerassimos Vlachos (1605/7-1685), Anastasios Papavasilopoulos, Vicentios Damodos (1700-1754), Methodios Anthrakites (†post 1748), Matthaios (Meletios) Typaldos (1648-1713), Georgios Sougdouris (1645/7-1725), Eugenios Voulgaris (1716-1806), Theodoros Kavalliotes (1718;-1789)  and Athanasios Psalidas (1767-1829).

In the Masters’ Theses and Doctoral Dissertations that were undertaken or are being completed under his supervision, philosophical inquiry is shaped by the apparent boundary of Ancient Greek, European and Modern Greek thought.