Child tracking system on large surfaces. The present invention allows use of low power wireless networks to implement a system to alert the minor loss of large areas, indoors or outdoors. It comprises an installed infrastructure consisting of a number of fixed nodes, and a set of mobile nodes to locate. There is also another set of terminals carried by the adults responsible for receiving notifications of loss. Communication between nodes meets a standard protocol for low power, short range Zigbee type. Locate each node sends its identification and information for your location. This information is sent by a multihop routing algorithm to the central module via node acting as a gateway. When the central module stops receiving packets with the identifier of a mobile node, it is considered lost, and a notification is sent to the terminal responsible adult.