To simplify the design of the cryo-instrument and to adapt it to the forms and dimensions of the organ undergoing surgery or of any other object a cryocatheter-tourniquet is proposed, where a thin-walled, flexible tube passed in a loop like-manner through the opening of another tube (after the type of a tourniquet), is used as a conduit of the cooling agent. The loop out on the object to be operated upon forms the working part of the cryosurgical appliance.