Memory devices based on C60 fullerene molecules and polystyrene and poly 4-vinyl phenol polymers are described. It is shown that the bistability in the I–V characteristics can be used to perform read-write-erase memory functions. In addition, it is demonstrated that mild thermal annealing enhances the stability of the devices. Specifically, after annealing, the hysteresis in our devices can be preserved up to 85°C in 60% humidity. Furthermore, memory retention tests show that it is possible to preserve a state even after annealing at 85°C in 60% humidity for 30min.