The results of the investigation on the synthesis and applications of halogen-free hybrid flame retardants (HFR) are presented. HFR were obtained by in situ modification of halloysite (HNT) with melamine cyanurate (MC). The reactions were conducted with and without the presence of poly(vinyl alcohol) (PVA) as a protective colloid. The modification of HNT was confirmed by using infrared spectroscopy (IR), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDS) and transmission electron microscopy (TEM) analyses. The thermal properties of flame retardants were investigated as well. The obtained HFR were introduced into polyamide 6 (PA6). The relationship between a type of HFR and its effectiveness in reducing the flammability as well as in improvement of mechanical properties of polymer composites was investigated. It was found, that depending on the type of applied HFR, the value of the oxygen index (OI) of the obtained composites was within 29–34.5 %. In turn, the use of PVA in the synthesis of HFR increased the flexibility of the compositions containing this type of HFR.