In vitro fermented robusta coffee is fermented coffee beans using lactic acid bacteria (LAB) isolated from the stomachs of civets. In vitro fermented robusta coffee was obtained by optimizing three variables, namely inoculum concentration, use of microorganisms Bifidobacterium bifidum and Lactobacillus plantarum and in vitro fermentation time using response surface methodology (RSM). This study aimed to produce fermented robusta coffee in vitro with optimal cupping test results using three variables that affect fermentation. The results of the RSM showed that the optimum cupping test results were 72.62, inoculum concentrations of 5% (w/v), in vitro fermentation time of 8 hrs and the ratio of B. bifidum/L. plantarum at a ratio of 1:0.