Abstract: A pneumatic door closer having an arming and latching mechanism that once armed permits a door to be held open by placing it in the desired open position and easily released by opening the door slightly, resetting the arming and latching mechanism permitting the door to be closed. A lever having a flat-profile spring over a substantial portion of its exterior surface is rotated into a position adjacent a latching washer causing the latching washer to canter upon a slight closure of the door, locking the door in an open position. Upon release of the door by further opening the door slightly, the cantered latching washer is released and a recoil spring causes the released latching washer to straighten or become uncantered, permitting a piston rod to move freely relative to the latching mechanism causing the door to close. The single piece lever and external flat-profile spring are easily manufactured and assembled and provides a reliable latching mechanism that can be conveniently operated with one hand.