Air pollution and traffic in Tehran have become a major challenge in recent years. By examining the data published by the Tehran Municipality, part of this challenge can be seen in the reduction in the number of Tehran city buses and the slow pace of their electrification. In this study, referring to the lack of financial resources in the contractionary state of the Iranian economy, financing methods through the capital market have been introduced. To find the best financing option for the electrification of Tehran buses, these options have been evaluated using the TOPSIS tool. Decision matrix data has been collected through a questionnaire from 21 experts in the field of financing. Finally, considering the four criteria of financing cost, size and capacity to absorb resources, time horizon and ease of process, lease-to-own bonds were ranked first. Also, in order to create sustainability in the process of fleet modernization and development, it has been suggested that the Ministry of Oil use the capacity to issue savings certificates for the municipality to complete lease-to-own bonds.