In aerospace applications, Commercial-Off-The-Shelf (COTS) Field programmable Gate Array (FPGA) is becoming increasingly attractive by offering low-cost solutions, simplicity and flexibility. This research faces the problem of disturbance induced by high energy particles on electronic devices. Based on detailed analysis of this phenomenon, the work is divided into two parts: in the first part evaluation of effects of the Single Event Upset (SEU) has been carried out with the aim of determining diagnostic techniques and the mitigation of this disturbance, taking into account the fact that testing is one of the fundamental points in electronic programmable devices; in the second part a fault tolerant technique has been devised so as to achieve the requirements demanded on a real avionic system.