A hydrogen detector with a porous layer of alumina. Pores with average pore diameters in the range of from about 10 to about 200 nanometers (nms) and average pore depths in the range of from about 10 to about 1000 nms have Pd nanoparticles in the pores forming a film. Electrodes on the Pd film measure changes in electrical resistance of the Pd film in the presence of hydrogen. Pd may be in the form of nanotubes. The alumina is anodized for various times to form the nanowalls or pores and vary the pore depths.