The micellization processes in the systems tetraethylene glycol monododecyl ether (C12E4)–heptane (1) and C12E4–Nile red–heptane (2) have been studied by electron absorption spectroscopy. In system 1, reverse micelles of small size appear, which makes it difficult to find the critical micelle concentration (CMC). In this regard, a method for determining CMC based on spectroscopic data was tested. The same one was done for system 2, where the appearance of Nile red as a C12E4 nano-adsorbent leads to the formation of protomicelles below the CMC. The CMC itself in system 2 turns out to be lower than the CMC in system 1, which corresponds to the predictions of the theory. The water role in the formation of reverse micelles was studied using a commercial analogue of C12E4 preparation Brij 30 (with a water content of 1%). The results obtained are consistent with theoretical predictions.