Abstract: A steam stop safety mechanism for a portable steam cleaner prevents discharge of steam at the cleaner nozzle when attaching and disconnecting attachments, even if the cleaner trigger is in a locked open position. The mechanism includes a steel pin that is displaced in an extended position against a shoulder in the nozzle to prevent pressurized steam from escaping the nozzle. Attachment couplings include a pin retractor plate with a central hub that pushes the pin away from the shoulder to allow the steam to flow through openings in the retractor plate and out a concentrator or attachment hose that has a trigger to release steam as desired.