We calculate the time-dependent metal production expected from starbursts and use them as boundary conditions in our 2D simulations of evolving superbubbles. We assume that the produced metals (oxygen and iron) thoroughly mix with the ejected stellar envelopes, and/or with the matter thermally evaporated from the superbubble cold outer shell. The metal production process determines the time-dependent metallicity in hot superbubble interiors, and leads to values of Z greater or equal than solar, when oxygen is used as tracer, and under-solar when the metallicity is measured with respect to iron. In either case, the enhanced metallicity boosts the X-ray emissivity of superbubbles, bringing theory and observations closer together.
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