The paper describes briefly an original methodology for the determination of the deposit thickness on the inside heat transfer surface of natural gas cooler and a procedure of its verification at the cooler CH_R of the booster station KS01 in Velké Kapušany. The methodology is based on the measurement of the degree of the gas cooling. It has the universal validity and can be used to determine the thickness of the deposits of all types of coolers working on any booster station.