A novel rubber filler, black liquormontmorillonite complex (BLMMT) was prepared by dehydration of a mixture of MMT and BL and used in the preparation of acrylonitrile butadiene rubber (NBR) composites by mechanical mixing method. The BLMMT/rubber composites were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and differential scanning calorimeter (DSC). Experimental results of XRD and TEM indicated that MMT was well-dispersed in the rubber because of the presence of lignin. DSC, thermo-oxidative aging measurements and TGA results demonstrated that the thermal properties of NBR were improved due to the addition of BLMMT. The tensile properties including tensile strength, elongation at break, and modulus were also tested. All experimental results indicated that this BLMMT complex could be an effective reinforcing agent in rubber for cost-saving and environment benefits. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013