A new open-source chemistry and aerosol box model BoxMART (Box Model for Atmospheric Research and Teaching) has been developed, aiming for easy and flexible configuration for various simulation cases, as well as suitable to teach and learn complex chemistry and aerosol processes. The model is written in Fortran and stored as a gitlab repository. The chemistry module is handled by KPP (Kinetic PreProcessor) which converts the chemistry scheme in an adapted format to Fortran code. The aerosol module currently includes coagulation, condensational and dissolutional growth, evaporation and aerosol thermodynamic processes. The MOSAIC (Model for Simulating Aerosol Interactions and Chemistry) model has been implemented to calculate the non-equilibrium dynamic gas-particle partitioning of non-volatile and semivolatile species, including H₂SO₄, HNO₃, HCl, NH₃, and organic compounds to multiple particle size bins. The current ion system includes H⁺, NH₄⁺, Na⁺, SO₄^2–, NO₃^–, Cl^– and H₂O, where pH value in each size bin is also calculated. The particle size distribution is discretized with a fully stationary method. In order to provide good examples for evaluating BoxMART, as well as future model development, a number of benchmark simulation cases from previous studies ranging from simple to complicated cases, have been revised in details and simulated to verify different processes.