A MEMS vibration energy harvester using an Aluminium Nitride (AlN) piezoelectric layer was designed, fabricated and characterized. The harvester was fabricated on an SOI wafer with a 30μm device silicon layer which serves as the structural beam on which a 0.5μm AlN layer is sandwiched between the top and bottom electrodes. The handle silicon serves as the proof mass. The harvester has a measured resonant frequency of around 114Hz and an average output power of 54nW was measured at optimal load and a low level of acceleration (24 mili-g). A 3D finite element model of the harvester was created in COMSOL Multiphysics and the obtained results are in close agreement with the measured data.