Abstract: An improved ball valve, particularly for gases, includes a case of unitary construction accommodating a hollow ballshutter supported between two juxtaposed gaskets and being controllable rotatively through a screw block having an external knob grip. The screw block accommodates, in addition to a gasket for the necessary seal, also a gasket capable of withstanding high temperatures. The screw block is held in place within the case by a bent wire segment of annular shape fitting in a specially provided annular seat formed in the case, and is located by a countersunk lockwasher.