The material balance of pyrolysis experiments performed between 580 degrees C and 820 degrees C is done on basis of results on various GC separation columns. The full analysis of cracked gas could be obtained by use of only two PLOT columns: a CarboPLOT column in connection to a micro thermal conductivity detector for determination of permanent gases and an alumina PLOT column for separation of all important hydrocarbons up to styrene detected by flame ionization detector. Decided supposition for accurate determination of condenseable components in cracked gas samples was the use of ＇＇Closeable Sampling Columns＇＇. A further progress was the creation of an modified method of gas chromatographic simulated distillation which can be used both for pyrolysis feedstock characterization and for liquid pyrolysis product analysis. This method is suitable for determination of the part of pyrolysis gasoline in total liquid product and for determination of important components boiling lower than 215 degrees C. Finally, the progress in the analysis scheme and making up the accounts is discussed.