A refueling algorithm using time-optimal control (TOC) for optimal switching of Natural gas vehicle (NGV) refueling with multi-level-pressure storage banks is presented. Fundamental issues in the development of simulation model for an NGV refueling system and methodology for optimization of the switching is discussed. Performance measures to evaluate and compare the proposed algorithm with a commercial NGV refueling algorithm are based on two criteria: refueling time and total mass stored, and are analyzed based on two experiments: the performance of refueling with fixed-level-pressure banks, i.e., a series of banks of same pressure and multi-level-pressure banks, i.e., a series of banks of increasing pressure. Results revealed the viability of TOC refueling algorithm when used in NGV refueling using multi-level-pressure banks. © 2021, The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.