Zirconium alloys are used extensively within the nuclear industry for structural components and fuel cladding, where their microstructure influences component performance. The final microstructure and properties are strongly influenced by the high temperature β phase microstructure, found during processing. To reconstruct this microstructure, a MATLAB based code was developed which includes analysis of the details of the orientation relationships between the parent β phase and child α variants. This enables deeper analysis of grain boundary types, and their influence on microstructural evolution (e.g. grain growth and hydride formation). In zirconium alloys, the final microstructure is controlled to optimise neutronic performance, and unexpected grain growth is detrimental to reactor performance. Previously, blocky-α grain growth has been observed in weld microstructures in short timescales with high temperature heat treatments (e.g. 1 hr @ 800 °C). In this work, in situ and ex situ heating experiments have been developed and used to study grain growth in these microstructures to enable the prediction of likely blocky-α grain growth from an initial weld microstructure, noting the influence of the prior-β grain boundaries. In-service, hydrogen ingress into Zr alloys can lead to the formation of brittle hydride phases which have a deleterious effect on the component performance. The misfit strain between hydrides and the matrix is thought to cause a localised stress field, which can influence hydride nucleation, growth, and reorientation. In this work, conventional EBSD and HR-EBSD were used to characterise hydride-matrix deformation fields near grain boundaries. These fields vary for hydrides that smoothly decorate the grain boundary and those that protrude into the matrix, providing insight into hydride-microstructure influenced component performance. In summary, this thesis provides microstructural characterisation of zirconium alloys to support the continued use of these alloys in demanding environments.