One of the preferences of modern organic synthesis is to replace conventional halogenation methods with more acceptable approaches. The main research goal within this thesis was therefore to investigate aerobic iodohalogenation of alkenes with I2/HCl/NaNO2/O2 reaction system which is based on the activation of I2 by in-situ synthesis of the reactive iodine(I) species HICl2. The method consequently represents an alternative option for atomic economical and mild iodination of organic compounds. In my research, I have investigated the application of the aerobic reaction system on four types of alkenes, namely: styrene, cyclooctene, 1-octene and trans 3-hexene. In general, reviews and final optimizations proved that iodochlorination of alkenes with HICl2 is successful and mostly selective choice. From regioselectivity point of view, it can be firmly concluded that iodine in the electrophilic addition is introduced to alkene as an electrophile I+. The main side reaction was found to be the incorporation of solvent 2,2,2-trifluoroethanol as nucleophile to iodonium intermediate and incorporation of water as nucleophile. Contrary to other alkenes, in the case of 1-octene, equimolar formation of both regioisomers is preferred, which is typical for terminal alkenes. What is more, I have also compared two types of synthesis. It has been proved that two-step iodochlorination of cyclooctene with pre-generation of HICl2 leads to more selective approach than one-step in-situ method, where HICl2 is formed in the presence of alkene. In the case of styrene one-step synthesis is more efficient. Contrary, iodochlorination of 1-octene and trans 3-hexene progresses equally successful when using either one- or two-step method.