A removable ladder step for providing a load support mountable to rung-ladders that have various rung cross-sections and/or various side rail depths. The removable ladder step has a load-supporting structure and a pair of adjustable holding devices connected thereto. The load-supporting structure has an upper wall connected to a front wall and to a rung-engaging wall. The upper wall configured to support a load thereon. A base member in a form of an elongated body is connected to the front wall and to the rung-engaging wall. An engaging space is formed in the rung-engaging wall for receiving and engaging a rung. Each of the adjustable holding devices has a holding member and a rail spacer connected thereto. The rail spacer is used to control a distance between a side rail and the holding member to accommodate ladders having various side rail depths.