Layered molybdenum disulfide (MoS2) has received significant attention due to various applications, such as catalysis, supercapacitors, batteries, and polymer nanocomposites. However, developing highly effective MoS2-based polymer nanocomposites with superior dispersion resulting in improved thermal and flame retardant properties still remains a huge challenge. Herein, a kind of MoS2 hybrid was synthesized by the reaction of exfoliated MoS2 nanosheets with (4-carboxybutyl) triphenylphosphonium bromide (TPP) via a cost-effective method, where TPP serves as a synergistic agent to further improve the dispersion and flame retardant efficiency of MoS2. Then the TPP-MoS2 hybrid was added to epoxy resin (EP) matrix to improve its fire safety properties. The hybrid was characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The TPP-MoS2 hybrid was uniformly dispersed in the matrix, leading to significant improvement of fire safety. After the addition of 2 wt% TPP-MoS2, the char residue of the EP nanocomposites was increased by 46% compared with that of pure EP, while the peak heat release rate (PHRR) and total smoke release (TSR) were reduced by 26% and 21%, respectively. The superior dispersion of the hybrid improved the physical barrier effect of MoS2 nanosheets thereby delaying the diffusion of volatile pyrolysis products and the transmission of heat and oxygen to underlying material. (C) 2019 Elsevier Inc. All rights reserved.