The article substantiates the necessity of participation of measuring laboratories of coke and coal industry enterprises in interlaboratory comparative tests. It is shown that the decisive factor in the accreditation or certification of testing laboratories is the reliability of the results. Thus, the regulatory documents governing the general requirements for the competence of laboratories specify a number of measures to ensure the quality of the results obtained. Among them, participation in inter-laboratory comparative tests (ILCT) is recognised as the most objective way to verify the reliability of the results obtained in a laboratory. The article defines the ILCT and explains the responsibilities of organisations entitled to conduct them. The data on the experience of the Testing Centre ‘Khartsis’ of SE ‘UKHIN’, approved by the NATIONAL ACCREDITATION AGENCY OF UKRAINE as a provider of verification of the professional level of laboratories in the field of testing lignite, hard coal, anthracite, products of their processing and blast furnace coke, foundry coke, coal coke, coke nuts, coke fines, are presented. In particular, the article analyses the results of four rounds of the Interlaboratory Comparison Programme for the Measurement of Coal and Coke Quality Indicators, implemented by the SE ‘UKHIN’ in 2023, in which measuring laboratories of coke and chemical enterprises, concentrating plants, mines, thermal power plants and other enterprises of various forms of ownership and departmental subordination participated. Using the example of actual results obtained, it is shown that constant participation in the Programme is an effective means of controlling the quality and reliability of the results issued by the laboratory, as it allows timely identification and elimination of the causes of poor quality measurements. Keywords: coal, coke, quality indicators, measuring laboratory, comparative interlaboratory tests, Programme, provider, control sample, round, certification, accreditation. Corresponding author: O.B. Sosnova, e- mail: lenas61.61@gmail.com