The combustion of premixed mixtures in two dimensional channels with symmetric sudden expansion has been studied numerically and experimentally. Steady asymmetric flames are obtained for Reynolds number (Re) above a critical Re value with asymmetric ignition of the cold mixture near the sudden expansion. Also, the asymmetric flame anchoring occurs if the transverse distance of ignition location is more than a critical value from the channel mid-plane. Below critical Re, a symmetric flame prevails even with asymmetric ignition. Numerically, with the established asymmetric flame as the initial condition, if the flow rate is reduced gradually, asymmetric flame becomes symmetric. However, the Re at which the flame becomes symmetric is lower than the value of critical Re, implying that the transition is hysteretic. If flame is initially symmetric, it remains symmetric with the increase in flow rate and only flame height of the symmetric flames increases. Experimentally, both the transition from symmetry to asymmetry and asymmetry to symmetry have been observed with the increase or decrease in flow rate respectively. Experimental observations support such hysteretic symmetric, asymmetric flame transitions past 2-D sudden expansion ducts. © Asia-Pacific Conference on Combustion, ASPACC 2019.All right reserved.