Among various red phosphors, Mn4+ activated fluoride hosts have received much attention due to their blue excitability and intense red emission. In this study we report a novel (NH4)3AlF6:Mn4+ phosphor, synthesized through a facile synthesis process avoiding high quantities of highly toxic HF acid. The synthesized host exhibit cubic structure in F-4 3m space group, with plenty of [AlF6]3+ octahedral sites. When activated with Mn4+ the crystal structure is retained and the material exhibits characteristic excitation bands with maximum around 469 nm and intense red emission around 631 nm. Furthermore, the thermal gravimetric analysis revealed the stability of composition up to 250 °C. The phosphor however exhibits high sensitivity to increased temperature and showed sharp quenching of luminescence at elevated temperatures.