This article is the third in a series of articles focused on presenting common methods for evaluating conventional and alternative fuels. The first two articles of the series were devoted to the determination of elements and non-hydrocarbon compounds in fuels [1]) and the determination of the physical properties of fuels [2]). This text presents an overview of the chemical properties determined for individual fuels. The chemical properties, acidity and alkalinity of fuels, content of unsaturated compounds, aniline point, water content, oxidation stability, and corrosive properties of fuels are presented in this article. The main goal of the article is to provide a comprehensive overview of which fuels are monitored, why they are monitored, and what methods are used for this monitoring. The emphasis is mainly on standardized parameters and tests, but in some cases, non-standardized tests are also discussed, or (additional) determinations not required by standards. For conventional and alternative fuels, several physical chemical, or other properties are used to evaluate the quality of these fuels. In this article, we present an overview of the chemical properties that are monitored for liquid and gaseous conventional and alternative fuels. These are acidity and alkalinity, content of unsaturated compounds, aniline point, water content, oxidation stability, and corrosive effects of fuels. In the article, we present the testing methods that are used to monitor these properties. Furthermore, we also present the reasons why these properties are monitored for individual fuels. Emphasis is placed on standardized parameters and tests, i.e., those prescribed by the relevant standards for individual fuels. However, parameters and alternative methods are also discussed, which are not prescribed by any standard for the respective fuels, but are supplementary determinations. The determination of elements and hydrocarbon and non-hydrocarbon compounds in fuels potentially falls within the scope of this article. However, since two separate articles [1] were devoted to these parameters, they will not be discussed here