The decision came after the team's home loss at the hands of Sporting Gijon on Sunday. The defeat was Espanyol's fourth in four games as they managed one win out of their previous 11 matches.
The club are now left trailing in seventeenth position with 12 points from 13 games.
"Marquez has been relieved from his duties as first team coach at the club," Espanyol's football director Francesco Herrera said.
A statement on the club's website added that assistant coach Oscar Perarnau will lead the team's Monday training. However, Herrera stressed his hope to appoint a new coach by Wednesday.
According to the Spanish media, former coach Luis Fernandez, Serbian tactician Miroslav Djukic and Jose Manuel Esnal are top candidates for the vacant position.