## 1 Introduction  
Measurements of systems' properties by non-destructive testing, which also include thermovisional methods, are currently being used in many fields of science and technology. The article focuses on the methodology supporting the state assessment of supercapacitors' samples. Tests and measurements were taken on the basis of commercially available supercapacitors. The development of the measurement methodology was carried out to verify the concept of defining additional parameters, which support the qualitative assessment of the tested capacitors. It was suggested to obtain additional information, regarding the properties of tested capacitors, based on the analysis of thermographic images that were obtained during the charging/discharging cycle while performing classical durability tests. Implementing thermovisional measurements to tests is related to the current spread of systems that enable measurements of infrared radiation (IR). Presently, the IR observation systems, widely available on the market, are an excellent tool for supporting a variety of developmental research. They allow for obtaining information concerning temperature fields of the surface in a short period of time and, on the basis of field distribution analysis, to conclude on the internal structure. On one hand, the suggested supporting measurement approach, the use of thermal imaging camera, is characterized by lower accuracy of temperature measurement of the examined object than the classically used calorimetric methods described in article [1]. Yet, it allows for more accurate illustration of the temperature field, as well as for indication of thermal energy transfer and the possibility of observing the entire sample being tested. The fundamental objective that was set during the implementation of the supercapacitors' non-destructive testing project was the attempt to acquire parameters such as average, maximum temperature increments, and methods of visualizing this areas, by proposed indicators based on sums of temperatures and variation coefficientfor qualitative assessment of examined samples on the basis of obtained thermograms. The article presents the following issues that were to be considered:  
* selection of the measurement system including both measurement instruments and the test stand,
* planning the test course sample preparation and the test course itself,
* implementation of data analysis algorithms, along with the selection of parameters obtained from thermovisional measurements that allows to support the quality of supercapacitors,
* measurements and the analysis of usefulness of suggested solutions and parameters supporting the assessment plus their further selection, and
* conclusions, along with information on observed restrictions and proposals for sequential changes. Recommended additional elements supporting the methodology of assessing the properties of supercapacitors were based on the analysis of temperature field fluctuations in relation to measurements of classical capacitor parameters. Measurements of basic parameters such as: change in capacitance (\(C\)) or change in equivalent series resistance (\(ESR\)--Equivalent Series Resistance), in connection with information derived from thermographic observations allow for a more comprehensive assessment of supercapacitors. Moreover, the article shows restrictions that were observed while using thermographic methods of qualitative assessment of supercapacitors samples. All of the tests were taken on supercapacitors that are commercially available on the market. The development of thermographic measurements is mainly due to the step-change of the available infrared radiation measurement tools, generally more accessible now in terms of cost and infrastructure.