A unique procedure for systematic group analysis of heavy petroleum products was developed and exemplified by acid tars as a type of refinery waste. Unlike the presently known procedures of analysis of crude petroleum and petroleum products, an advantage of this method is the successive complete separation of petroleum refining products into components by extraction in a Soxhlet apparatus followed by the adsorption of some components. The procedure makes it possible to determine the fractional group composition of a representative sample of acid tar from one of the storage ponds in the Nizhni Novgorod oblast.