A primary method if used in pulverized oil shale-fired boilers in operation enables one to achieve the target value of SO2 specific emission 400 mg/Nm(3). It is also possible to meet the SO2 specific emission limit value, 200 mg/Nm(3), set by the European Union for the new-installed solid fuel boilers by further optimization of the technological parameters of pulverized oil shale firing on the basis of primary methods. The intermediate injection of water (one of the primary method measures) during the test (the offered solution is somewhat similar to the LIFAC method) after the superheater decreases the SO2 emission from 2146 to 1760 mg/Nm(3), i.e. by 17%. At the same time, the production of steam in the boiler decreases from 285 to 260 t/ h, i.e. by 25 t/h. The performed tests proved to be technically ineffective and failed to give expected results.