The present work investigates hydrate equilibrium conditions for tetra-n-butyl ammonium bromide (TBAB) + methane + water mixtures. The experiments are carried out in the TBAB mass fraction range of (0.05 to 0.45) and in the pressure range of (0.5 to 7.0) MPa. The experimental results show that the presence of TBAB decreases the formation pressure of methane hydrate. Moreover, pressure reduction is dependent on the TBAB concentration.