This review covers the electronic, optical and electrochemical properties along with electronic behaviors of boron (B) and nitrogen (N) substituted Single Wall Carbon Nanotubes (SWCNTs) underlying density functional theory (DFT) simulations. It is intended to be of interest for both experimentalists and theorists to expand application in the fields of SWCNTs. In particular, this article will focus on the electronically driven optical properties of CxNy nanotubes as a function of N concentration and BxCy nanotubes as a function of B under the action of a uniform electric field with various polarization directions through relaxed C-C bond length rib initio DFT. The link between the electronic band structure and the peak of the loss function will be highlighted. Within the formalism of DFT, we also consider the aspects of vacancy-defected SWCNTs. The effect of nitrogen incorporation is quite pronounced in enhancing the electrochemical properties of CNTs. In fact, this is a growing field due to the need of developing next-generation H-based energies. Finally, an attempt will be made for a comparative study of these theoretical results with experimental ones. Although there are ample experimental reports of N incorporation, at least less than 10%, in the nanostructured carbon, the experimental results on B-alloyed and N-alloyed SWCNTs are scarce. The review concludes with an outlook on the technological potential of these nano-composite systems as optical devices and nano-sensors. (C) 2013 Elsevier Ltd. All rights reserved.