This paper presents a new mesh conversion template, called HEXHOOP, that fully automates a conversion from a hex-dominant mesh to an all-hex mesh. A HEXHOOP template subdivides a hex/prism/pyramid element to a set of smaller hex elements while maintaining the topological conformity with neighboring elements. A HEXHOOP template is constructed by assembling subtemplates, cores and caps. A dicing template for a hex and a prism is constructed by choosing the appropriate combination of a core and caps. A template that dices a pyramid without losing conformity to the adjacent element is derived from a HEXHOOP template. Some experimental results show that the HEXHOOP templates successfully convert a hex-dominant mesh to an all-hex mesh.