Transition metal dichalcogenides (TMDCs), such as MoS2, are two-dimensional materials with exciting perspectives for application in (opto-)electronic devices or catalysis. Within the three known polytypes (1T, 2H, and 3R) of this material, 2H-MoS2 is of particular interest due to its semiconducting nature and thickness-dependent band gap. Apart from the established synthetic pathways toward 2H-MoS2 with defined layer thickness, including mechanical or liquid based exfoliation and chemical as well as physical vapor deposition, wet-chemical techniques affording colloidally stable TMDCs have recently emerged, which are based on principles originally developed for the synthesis of colloidal quantum dots. Some advantages of wet-chemically synthesized TMDCs are their scalability, relative ease of purification and solution-processability, which render them particularly suitable for application in LEDs or solar cells. For these applications, detailed knowledge of the electronic structure, such as the exact position of the band edges, is crucial to design efficient device stacks, in which the layers of several materials, e.g. electron-/hole-conducting and blocking layers as well as the active layer are electronically matched. Standard electrochemical investigations, such as cyclic voltammetry (CV) or differential pulse voltammetry (DPV), can provide such information, which are much easier and usually faster to perform compared to ultraviolet photoelectron spectroscopy or scanning tunnelling spectroscopy investigations. However, a short-coming of standard electrochemical techniques is the lack of differentiation between band edges and trap states, which is only afforded by combining electrochemistry with optical spectroscopy. Such spectro-electrochemistry detects changes in the absorption or luminescence of a sample upon oxidation or reduction. This way, the band edges or energy levels involved in a specific optical transition can be identified by determining the potential at which this transition bleaches, either due to electron injection into the final state (reduction) or a depletion of electrons in the initial state (oxidation). In contrast, reducing or oxidizing trap states will have a minor effect on the absorption spectrum, allowing for the distinction between band edges and trap states.