In this study, low-temperature synthesis of a Nb2SnC non-MAX phase was carried out via solid-state reaction, and a novel approach was introduced to synthesize 2D Nb2CTxMXenes through selective etching of Sn from Nb2SnC using mild phosphoric acid. Our work provides valuable insights into the field of 2D MXenes and their potential for energy storage applications. Various techniques, including XRD, SEM, TEM, EDS, and XPS, were used to characterize the samples and determine their crystal structures and chemical compositions. SEM images revealed a two-dimensional layered structure of Nb2CTx, which is consistent with the expected morphology of MXenes. The synthesized Nb2CTxshowed a high specific capacitance of 502.97 Fg−1at 1 Ag−1, demonstrating its potential for high-performance energy storage applications. The approach used in this study is low-cost and could lead to the development of new energy storage materials. Our study contributes to the field by introducing a unique method to synthesize 2D Nb2CTxMXenes and highlights its potential for practical applications.