The q-classical orthogonal polynomials defined by Hahn satisfy a Sturm-Liouville type equation in geometric differences. Working with this, we classify the q−classical polynomials in twelve families according to the zeros of the polynomial coefficients of the equation and the behavior concerning to q-1. We determine a q-analogue of the weight function for the twelve families, and we give a representation of its orthogonality relation and its q-integral. We describe this representation in some normal and special cases (indeterminate moment problem and finite orthogonal sequences). Finally, the Sturm-Liouville type equation allows us to establish the correspondence between this classification and the Askey Scheme.

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