His main research interest was in the field of computational chemistry. Basch was a pioneer in computational quantum chemistry, in developing methods and innovative applications of theoretical concepts and equations to solving problems in chemistry. Already in 1962, as a beginning graduate student at Columbia University, he recognized the potential use of the computer (which then filled a whole building), in chemical research. The methods and paradigms he developed are used today in modern software packages for the calculation of molecular properties. The list of applications he has been involved in include electron, electronic and photoelectronic spectroscopies, energetics, geometric and electronic structures, chemical reaction paths, intermediates, and transition states, metal-ligand, metal-metal, metal cluster bonding, and active site reactions in metalloenzymes. The theoretical methods include single and multi-configuration molecular orbital theory, valence bond theory, and effective core and effective fragment potentials.
His latest research efforts were directed towards finding appropriate molecular bridges that can serve as nano-conducting and switching elements in molecular electronics. 
During his career, Basch published more than 180 papers and book chapters.