Ionic Liquids (ILs) are organic compounds composed merely of ions and with melting points generally below 100°C. Many ILs have melting points around room temperature and are known as room temperature ionic liquids (RTILs). RTILs have attracted great interest for practical applications over the past few decades due to their unique properties such as negligible vapor pressure, low flammability, high thermal, chemical and electrochemical stability and good solvating properties. Additionally, properties of ILs can be tuned by changing the structure of the cation and anion. ILs have been studied for electrochemical applications in this work from the following three aspects: (1) Electrocatalyst for electrochemical reduction of CO2. It found that ionic liquid [emim][Tf2N], when used as a supporting electrolyte and electrocatalyst, was not only able to decrease the reduction overpotential for CO2 reduction, but can also alter the reaction pathway. The results highlight the ability of [emim][Tf2N] to modulate the CO2 reduction products. (2) Solvents for electroplating of chromium from trivalent chromium sources. A series of imidazolium chloride ionic liquids with varied cationic alkyl chain lengths were used for electroplating of chromium with chromium chloride hexahydrate (CrCl36H2O) as the chromium source in this study. Chromium coatings with comparable properties compared with the conventional commercial chromium coatings were obtained, revealing a potential of using this type of mixtures as a more environmentally friendly alternative to the conventional practice to produce chromium coatings from highly toxic hexavalent chromium (Cr(VI)) aqueous solutions.  (3) Electrolytes for renewable energy storage devices such as lithium-ion batteries. A series of RTILs containing different aprotic heterocyclic anions (AHAs) were synthesized and characterized as potential electrolyte candidates for lithium-ion battery applications. The results showed that many of the AHA RTILs exhibit very good conductivity for their viscosities as identified by the exceptionally high molar conductivity ratio. Further investigation on the effect of addition of lithium AHA salts on the transport properties of the lithium salt/IL mixtures showed that lithium ions, although with a smaller size, diffuse slower than the cation and anion of the IL, which is a strong indicator of the existence of complexes formed by lithium and anions. Consistent with previous studies, significant increase in viscosity and decrease in ionic conductivity with addition of lithium salts were observed for the three AHA RTIL based mixtures. This reinforces the necessity to search for approaches to alleviate such effects caused by addition of lithium salts in order to make the lithium salt/IL mixtures practically suitable as electrolytes for lithium-ion battery applications.