A possibility for evaluation of oil potential of two Estonian shales and six biomass samples by Rock-Eval data is described. The amount of hydrocarbons volatilized from thermo-labile ingredients of the samples at 300 degrees C (S1) is found to increase from 1.1 to 66.3 mg/g in the row: Dictyonema < kukersite < peat < pine sawdust < pine bark < willow < reed approximate to spruce branches. The total oil potential by pyrolysis at 300-650 degrees C (S1+S2) increases from 47.4 to 367 mg/g in the row: Dictyonema < peat < reed < pine bark < willow energy crop < spruce needles < pine sawdust < kukersite. An increase in oxygen index decreases the temperature at the pyrolysis maximum rate and S2 but increases S1 of the samples according to relationships approximated to linear regressions.