Supermassive black holes (SMBH) are believed to reside in the center of every galaxy. The primary characteristic of these SMBH is their mass. However the SMBH mass was actually measured only for a few tens of objects as the observational methods for such measurements are limited. One of these methods is reverberation mapping which can be applied to Type 1 Active Galactic Nuclei (AGNs). Using reverberation mapping the SMBH mass in about 45 AGN was measured in the past 25 years. However, all these AGNs have moderate mass (10⁶-10⁸ solar mass) and luminosity (10⁴² to 10⁴⁶ erg/sec). To gain better understanding about SMBH there is an essential need to study the low and high mass AGNs. This talk will present first results from an on going study to measure the lowest mass AGNs using the reverberation mapping technique with the Hobby-Eberly Telescope (HET).