A printing apparatus employing a print head comprising a plurality of thin wire print electrodes mounted in a single plane and held in a closely-spaced row by an electrically insulating resilient material so that the wires are individually movable out of the planar alignment to a limited extent with respect to the other wires in the array. A relatively rigid backing member is provided to support the electrode array and the print head is mounted in a relatively fixed position relative to the print ribbon and a predetermined pressure is produced between the print head and the electrothermal print ribbon during printing operations.