Selected examples of the Canadian contribution to the development of understanding of the behavior of hydrogen in zirconium alloys reviewed. To solve the technical problems faced by the nuclear industry, it was necessary to have values for the solubility and diffusivity of hydrogen in the alloys, the diffusivity needed for the three gradients of concentration, temperature, and stress. With these quantities known, sensible models for the accumulation of hydrogen at points in the reactor components and the morphology of the resultant hydride phase were developed. The original paper was published by ASTM International in STP 1354, Zirconium in the Nuclear Industry: Twelfth International Symposium, 2000, pp. 32–48.