While NOx storage and reduction is periodically operated, steady-state studies have been widely carried out to investigate the involved reaction mechanisms and effects of operating parameters. Due to the complex reaction chemistry and its coupling with transport phenomena, multiplicity may exist. A steady-state monolith reactor model accounting for microkinetics and reaction heat effects was proposed in this study to avoid the evaluation of enthalpies of microreaction steps. Three simplified versions of the monolith model were developed based on various assumptions of the axial gradients. Steady-state behaviors of NO/O-2/C3H6 system were investigated. A predictor-corrector (PC) continuation method that does not require explicit evaluation of Jacobian Matrix was developed to solve the nonlinear system with a variable parameter of feed temperature. Model predictions were compared with experimental results. (c) 2013 American Institute of Chemical Engineers AIChE J 60: 623-634, 2014