We present extensive atomistic molecular dynamics simulations of the structure and stability of fullerene-based membranes. The simulations provide a molecular description of the PhK (pentaaryl[60]fullerene anions, C60Ar5 center dot K+) and C8K (C60Ar5 center dot K+ with octyl substituents) membranes. Physical chemical properties and molecular organization of PhK and C8K membranes elucidate various aspects related to their formation and potential applications. Our simulations evidence that such membranes are robust and stable. PhK membranes proved very stable and compact. Considering experimental evidence, PhK bilayer is an adequate model for the surface of the PhK vesicle.