The line opened on 4 February 1885 as a single-track, metre-gauge railway from Attiki Square in downtown Athens to Kifissia.

The headquarters of Attica Railways, along with a rolling stock depot, repair workshops and goods sidings were located at Attiki Square, next to Liossion street.

In 1926, the line was transferred to the Electric Transport Company (Greek: Ηλεκτρική Εταιρεία Μεταφορών, or ΗΕΜ), a member of the Power and Traction Finance Co. group.

After 1926, trains to Kifissia again departed from Attiki station, and the section between Lavrion Square and Attiki Square was served by tram route K.[1] The Electric Transport Company operated the line until 8 August 1938, when it was closed pending electrification works, which were interrupted by World War II.

This was done to continue the planned renovation, gauge conversion and electrification works which had been interrupted by World War II.