The square cooler is a machine designed mainly for cooling the pellet coming from the pelleting press. The cooling technique used by this machine can allow a minimum impediment, i.e. an easy installation also in the existing plants, a reduced consumption of energy, simple and versatile adjustable control of stay time of the product in the cooler, and a continuous unloading flow of the product itself. The constructive structure is extremely simple in order to require a minimum maintenance. The cooler consists of one product storage chamber, variable in size according to the type, on which base is mounted a special unloading device consisting of one fixed screen with shaped profile for a good product flowability without any stagnation, and by a mobile screen underneath, which determine the opening of the screen slot namely, the product downflow.