Recent advances in optical sensors show promise for the development of new wide area monitoring and distributed optical network hydrogen detection systems. Optical hydrogen sensing technologies reviewed here are:open path Raman scattering systems,back scattering from chemically treated solid polymer matrix optical fiber sensor cladding; andschlieren and shearing interferometry imaging.Ultrasonic sensors for hydrogen release detection are also reviewed. The development status of these technologies and their demonstrated results in sensor path length, low hydrogen concentration detection ability, and response times are described and compared to the corresponding status of hydrogen spot sensor network technologies.