This paper reports the dielectric and glassy behavior of 70(Na0.5Bi0.5) TiO3-30SrTiO3 (NBT-30ST) lead-free perovskite relaxor. The temperature dependent dielectric data indicates that the material undergoes a diffuse phase transition at Tm (temperature corresponding to maximum dielectric constant) with diffuseness coefficient γ∼2. The material also shows frequency dispersion around Tm with a high ΔTm (Tm,1MHz-Tm, 0.1kHz) value of ∼42. The above parameters manifest strong relaxor behavior of NBT-30ST. Moreover, the results are analyzed by employing empirical models such as V-F law, Power law to explore the glassy behavior associated with the system. The frequency dependent Tm analysis revealed greater interactions between the polar nano regions (PNRs). For further information on PNRs, the dielectric behavior at much higher and lower temperature than Tm has also been analyzed. © 2016 Author(s).