The rising emissions of carbon dioxide due to the industrial development of our society are contributing to accelerate global warming. As a consequence, recent years have witnessed the development of processes for the fixation of CO2 into organic molecules. Although the chemical utilization of CO2 will most likely not dramatically reduce its concentration in the atmosphere, its low cost and high availability could potentially help replace some of the established industrial processes that contribute to climate change. In particular, the carboxylic acid motif is present on a myriad of pharmaceuticals, agrochemicals or plastics, among others, making their synthesis an ideal target for CO2 utilization. Unlike traditional carboxylations of highly polarized and sensitive organometallic reagents, reductive carboxylation reactions offer the possibility to employ simple electrophiles for the synthesis of these desirable molecules, thus representing a formidable alternative to such nucleophilic entities. These doctoral studies have focused on the development and understanding of new, simple, and practical reductive carboxylation reactions to produce carboxylic acids from inexpensive and abundant electrophiles by means of Ni catalysis.