Abstract: A composting toilet for composting toilet waste, which toilet comprises a composting chamber, in which the toilet waste is received and when needed is mixed with a decomposition-boosting material in order to decompose this compost into humus, a humus-collection box, which is located underneath the composting chamber for collection and emptying of the humus from the composting chamber, and a grid positioned between the composting chamber and the humus-collection box and formed with through-passage openings, said grid arranged to support the compost and to allow fall-through of the humus from the composting chamber to the humus-collection box. Underneath the grid a sliding damper is arranged for regulation of the degree of openness of the openings in the grid and of the fall-through of the humus in order thus to control the decomposition process in the composting chamber by regulation of the moisture balance in the compost contained in the composting chamber.