Vitrinite reflectance data in Hungary are mainly used for hydrocarbon exploration in the Neogene basins. However, enough data are available from secondary reworked vitrinite populations to help determine the source areas and maturation history of older reworked sediments within the Neogene basins. This reworked material is derived mainly from Paleogene to early Paleozoic deposits that were uplifted and eroded during Tertiary time. A simple model describing the maturation of reworked vitrinite gives results in good agreement with observations. This model explains how a discontinuity in vitrinite reflectance can occur across an erosional unconformity, and why this discontinuity may disappear with heating of the sediment pile over a sufficiently long time period. Vitrinite d ta are also sensitive to local heating caused by magmatic intrusions. This makes it possible to distinguish between intrusive and extrusive igneous rocks using vitrinite data, and to predict the existence and location of intrusive igneous rocks that have not been penetrated by drilling.