This experiment is aimed to study the effect of Oxygen on deformation mechanisms in Zr alloys with a particular emphasis on studying twinning. Oxygen is found in many Zr alloys used as cladding material by the nuclear industry. An important aspect of the cladding material is the crystallographic texture. Radial basal texture is most desirable, because of the way hydrides form during service. The texture evolution is also closely linked with twinning. During pilgering (process of make seamless tubes), the radial direction is the main compressive direction when wall thickness is reduced. Therefore, a radial basal texture can be generated but its strength will depend on the ease of activating that particular twinning mode and deformation by slip. The interstitial Oxygen strengthens the material but it has also been observed in the past that Oxygen might reduce twining activity in Zr alloys.