The notion of quantoid is an analogy to the notion of matroid in the context of quantum realm. This thesis summarizes basic properties of quantoids and the correspondence between quantoids and selfdual matroids. A new set of axioms is derived as an alternative to the set which was used as the original definition of quantoid. A catalog enumerating all quantoids with the size of their ground set up to 5 elements is attached in the appendix and a larger database of quantoids (up to 7 elements in the ground set) is enclosed as an attachment of this thesis.