The effect of microcapsulated red phosphorus (mRP) was studied on the flame retardant, thermal and mechanical properties of thermoplastic polyurethane (TPU) composites containing Huntite&hydromagnesite (HH). The flame retardant properties of TPU based composites were investigated using limiting oxygen index (LOI), vertical burning test (UL 94), thermogravimetric analysis (TGA) and mass loss calorimeter. The mechanical properties of composites were studied using tensile test and dynamic mechanical analysis (DMA). According to the test results, the adjuvant effect of mRP was observed in terms of both flammability and mechanical properties of composites. The highest LOI value (32.5), the highest UL-94 rating (VO) and the lowest pHRR (155 kW/m(2)) value were observed with the partial substitution of 7 wt% mRP with HH. The tensile strength also increased at about 60% with respect to TPU/50HH. The mRP showed the synergistic effect by increasing the barrier effect of residue in the condensed phase and the formation of active radicals in the gas phase. The mRP showed adjuvant effect on mechanical properties due to the plasticizing and compatibilizer effect of low molecular weight epoxy resin carrier. (C) 2016 Elsevier Ltd. All rights reserved.