In a real IoT architecture we can often find a big number of devices, usually located in remote or inaccessible areas where manual intervention is generally cost prohibitive and sometimes really difficult. So since all these devices are made to be durable and have a long lifetime, they need to be constantly upgraded during time and this is why the firmware update plays a critical role in maintaining the architecture performance at its best. The solution to this particular problem is called Firmware Over-The-Air (FOTA) and it consists in different methods made to remotely provide an efficient and timely firmware update for this kind of devices.For all these reasons, a new research area is now evolving trying to build always new and better solutions for this particular scenario where not a large number have been proposed yet.In this thesis a new FOTA method is evaluated with the purpose of guaranteeing the firmware update process in heterogeneous Low Power IoT networks, exploring the implementation details and quantifying the costs in terms of energy, throughput and time required to complete the operation.This method uses the OMA-LwM2M Device Management and Data Model standard along with the CoRE CoAP application protocol over the 6LoWPAN communication protocol to enabling M2M communication.