Supercapacitor (SC), also known as ultracapacitor or electric double layer capacitor has found wide application areas to be used as stand-alone energy storage devices or in combination with other energy storage technologies like battery and fuel cell. Some of the potential applications are flash memory, wireless sensor network (WSN), electric vehicle (EV), smart meters, etc. These applications demand power security from their energy source, which can be ensured via continuous monitoring of the remaining charge and health of the device. In this paper, we propose a Particle Filter (PF) based online estimation scheme for estimation of State-of-Charge (SOC), State-of-Health (SOH) and temperature of SC by combining electrical equivalent circuit model (ECM) and thermal model. In particular, we monitor the SOH of the SC via real-time estimation of equivalent series resistance (ESR) and capacity of the device. Finally, we verify the effectiveness of the proposed scheme via a simulation study. We found that the PF based estimation scheme is performing with acceptable accuracy.