Development of a nonconforming eight to 26-node hexahedron for three-dimensional (3-D) thermal-elasto-plastic finite element analysis (FEA) is presented. The nonconforming element satisfies the MacNeal and Harder patch test and does not lock in plastic deformation, eliminating the need for selective reduced integration. The enhanced displacement and strain fields are fully consistent with a linear thermal strain field. In some cases this eliminates the need for isothermal elements in thermal-elasto-plastic FEA. Several cases are presented for validation purposes. In addition, a 3-D thermal-elasto-plastic analysis of a weld is presented, using selective reduced integration and nonconforming elements with both constant and linear thermal strain fields. The nonconforming elements show improved behaviour over selective reduced integration, but are found to be about 20% more expensive on a per iteration basis when all the elements are replaced. However, for the problem considered, the nonconforming elements provide about 2.5 times more degrees of freedom (DOF). Adaptive processes could reduce this by utilizing nonconforming elements only where they are required.