For the real-world application, MO-E-EQI was implemented to guide the optimisation of an esterification reaction. Four variables, flow rate, catalyst (DMAP) loading, equivalent and temperature were adjusted to maximum STY while minimize E-factor simultaneously. Initial 20 sampling points were generated by MaxPro and experimental data with three samples was collected for each condition. Based on these data, GPs were trained and optimization was sequentially continued for a further 40 steps with β = 0.6. The non-aggressive method was used for the MO-E-EQI criterion.