III-nitride based Quantum Wells (QWs) have been extensively studied as active buildings blocks for different electronic and optoelectronic devices. Several samples of GaN/AIN Axial Multi Quantum Well nanowires (MQW NWs) have been synthesized, leading to NWs with a MQW structure with GaN wells of different widths along the growth axis, 1.5, 2,3 and 4 nm. In this work structural and optical properties are studied by means of high resolution transmission electron microscopy (HRTEM) and photoluminescence (PL) analysis respectively.