Arc discharge is commonly used for the synthesis of carbon nanotubes (CNTs), even though not much is known concerning the process itself and the role of the discharge parameters on the formation of different kinds of nanostructures. We have investigated the formation and the morphology of the C deposit on the cathode, after arc discharge between two graphite electrodes immersed in liquid nitrogen. The deposit consists of disordered carbon structures at the bottom and on the external part of the deposit, forming like a bowl that contains randomly oriented CNTs, aggregated in several pillars in the internal part and on top. We have found that the applied voltage not only influences the macroscopic structure of the C deposit, but also the structural properties of the individual CNTs.