Surface-modified aluminum hydroxide and magnesium hydroxide mixtures (SAMHs) were filled with linear low-density polyethylene (LLDPE) with a maleic anhydride grafted polyethylene (PE) compatibilizer to produce a SAMH master batch, which was then dispersed in polyamide 6 (PA6) to yield a PA6/PE/SAMH (50/20/30 by weight ratio) ternary composite. Through such a master-batch method, an effective flame retardance UL94 V-0 rating at a 3.2 mm thickness with a 33% limiting oxygen index was achieved. The flame-retardance mechanism of the ternary composite was investigated by thermogravimetric analysis and scanning electron microscopy/energy dispersive X-ray spectroscopy analysis. A cocontinuous PA6/PE polymer host and a preferential dispersion of SAMH particles in the matrix induced the formation of a compact flame-resistant char layer and a high residue rate during burning; this resulted in the desired flame retardance of the ternary composite. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 117: 3370-3378, 2010