This invention relates to a field emission cathode (1) for a light source. The cathode (1) comprises at least one base body (3) having an emission surface (3'). Further, the base body (3) is formed by a structured material, and the emission surface (3') is at least partly covered by a field emitting nano-structured material (2). Moreover, this invention relates to a light source, comprising an anode (5), a cathode (1) and an evacuated container (6) enclosing the anode (5) and the cathode (1). The container (6) have at least one inner wall being provided with a luminescent layer (4) as well as a conductive layer forming said anode (5) and the cathode (1) is a field emission cathode of the above mentioned type.