Laser-induced breakdown spectroscopy (LIBS) was used for the quantitative assessment of the calorific value of Estonian oil shale. Samples were collected from different layers of oil shale and limestone from Narva open cast mine, Estonia. Lumps of crushed oil shale without any special preparation were tested on a mock-up of a moving conveyor belt. The moisture content of oil shale samples was varied. Multivariate regression analysis was applied for processing of spectroscopic data. The results obtained using the bomb calorimetric method were used for calibration. The method for selecting the optimal number of spectral lines for data processing is presented. The standard deviation of prediction of the calorific value was 1.76 MJ/kg and the moisture content was 1.94%.