Abstract: A line for decorating and controlling products, in particular ceramic tiles and the like, includes a conveyor of products to be decorated, at least one decorating device of the jet type actuated by piezoelectric-control nozzles adapted to apply at least one layer of enamel on the products passing on said conveyor; the line further includes at least one control and diagnostic module of the decorated products, provided with means for detecting decoration and/or structural defects of the products themselves.