Telematic appliance for vehicles, comprising electronic processing means installable on a vehicle, wherein said electronic processing means comprises: - at least a management and control unit adapted to manage and control information relating to said vehicle, - at least a communication unit associated with said management and control unit and adapted to communicate with at least a remote processing unit, - at least a locating device for locating the position of said vehicle, and - at least a device for measuring the instantaneous acceleration/deceleration of said vehicle, wherein the telematic appliance comprises electric connection means adapted to connect said electronic processing means to said battery; the telematic appliance being characterized by the fact that comprises support means made up of a substantially box-shaped container body which completely houses the electronic processing means and fastening means adapted for fixing said box-shaped container body onto an upper portion of said battery, and by the fact that said electric connection means are composed of a pair of power cables connected to the electronic processing means 2 and having, at the free extremities, respective electric connectors that can be directly connected to the positive electric pole (P+) and to the negative electric pole (P-) of the battery, the telematic appliance being further characterized by the fact that said electronic processing means comprise storage means adapted to store an identification code of the appliance and an identification code of the vehicle, and that said electronic processing means comprise verification means configured to check whether said identification code of the appliance and said identification code of the vehicle are correct or not, wherein said electronic processing means are connectable with an anti-ignition device of said vehicle and are adapted to force an engine cut in the case of said verification means detecting that at least one between said identification code of the appliance and said identification code of the vehicle is incorrect. - at least a management and control unit adapted to manage and control information relating to said vehicle, - at least a communication unit associated with said management and control unit and adapted to communicate with at least a remote processing unit, - at least a locating device for locating the position of said vehicle, and - at least a device for measuring the instantaneous acceleration/deceleration of said vehicle, wherein the telematic appliance comprises electric connection means adapted to connect said electronic processing means to said battery; the telematic appliance being characterized by the fact that comprises support means made up of a substantially box-shaped container body which completely houses the electronic processing means and fastening means adapted for fixing said box-shaped container body onto an upper portion of said battery, and by the fact that said electric connection means are composed of a pair of power cables connected to the electronic processing means 2 and having, at the free extremities, respective electric connectors that can be directly connected to the positive electric pole (P+) and to the negative electric pole (P-) of the battery, the telematic appliance being further characterized by the fact that said electronic processing means comprise storage means adapted to store an identification code of the appliance and an identification code of the vehicle, and that said electronic processing means comprise verification means configured to check whether said identification code of the appliance and said identification code of the vehicle are correct or not, wherein said electronic processing means are connectable with an anti-ignition device of said vehicle and are adapted to force an engine cut in the case of said verification means detecting that at least one between said identification code of the appliance and said identification code of the vehicle is incorrect.