The aim of this study was to investigate the effects of probiotic Bacillus indicus HU36 and dietary fibers (maltodextrin and lemon fiber) addition on color and organoleptic quality properties of dark chocolate. The viability of B. indicus HU36 in dark chocolate was examined as well in the study. Three-level [1.5, 3.5, 5.5 (g/100 g)], two factorial (maltodextrin, lemon fiber) Central Composite Design (CCD) was performed for developing synbiotic chocolate formulation. According to our results, B. indicus HU36 showed survival rate between 88 and 91% in samples. Descriptive sensory analysis (QDA (R)) and color analysis were performed to examine the effects of factors and their levels on quality attributes and describe developed chocolates in detail. While bacteria and dietary fiber addition did not show any negative effects on product sensory and color properties; dietary fiber addition improved some sensorial features significantly i.e. sweetness, firmness and adherence, The validation of the model had been accomplished by applying the conditions generated by the RSM model. This study is the first report on the use of B. indicus HU36 in potentially probiotic chocolate production. (C) 2013 Elsevier Ltd. All rights reserved.