This paper presents the comparison of electrical performance of symmetric toggle switch (STS) by incorporating hafnium oxide (HfO2) as a dielectric layer instead of silicon dioxide (SiO2). Change in dielectic layer leads to the change in ratio of down to up state capacitance, which determines the performance of capacitive type RF MEMS switches. Simulated results show that for the same switch dimensions, response of the SiO 2 based switch is in X-Band (8-12 GHz), whereas the switch having HfO2 as a dielectric layer shows the resonance in C-Band (4-8 GHz). The advantage can be utilized for optimizing the size of STS to shift the operating frequency range in X-Band. Simulated isolation and insertion loss are also better in case of the optimized STS with HfO2 dielectric layer; -43 dB and -0.014 dB for 11 GHz respectively as compared to SiO2 dielectric layer with isolation of -29 dB and insertion loss of -0.016 dB at 11 GHz. The measured isolation for a SiO2 device over the frequency range of 9-13 GHz is better than -20dB. For the similar device dimensions, STS with HfO2 dielectric layer shows isolation better than -20 dB from 4-11.5GHz.