In 1877–78 he participated in a study trip to Greece and Italy under the aegis of the Deutsches Archäologisches Institut.
As a result of this research, he published with Adolf Furtwängler, Mykenische Thongefäße, a landmark work that provided important historical timelines for Mycenaean pottery.
In their investigations of Mycenaean pottery, Loeschcke and Furtwängler gave distinctions between it and Geometric pottery.In 1879 Loeschcke became a professor of philology and archaeology at the University of Dorpat, where he co-authored another important work on Mycenaean pottery with Furtwangler, titled Mykenische Vasen (1886).
In 1913 Loeschcke was appointed a member of the Prussian Academy of Sciences.
Loeschcke performed archaeological investigations of "Limes Germanicus", which were a series of frontier forts that bounded the ancient Roman provinces of Rhaetia and Germania Superior.
He also performed investigations at the Kaiserthermen (Imperial Baths in Trier) and at the Roman camp in Haltern.