The frequency and bias voltage dependent of the capacitance-voltage (C-V) and conductance-voltage (G/w-V) characteristics of Sn/p-InP Schottky barrier diodes (SBDs) were investigated in the frequency range of 100 kHz-7 MHz at room temperature. Experimental data shows that the measured capacitance (C-m) and conductance (G(m)/w) increase with decreasing frequency due to a continuous distribution of (N-ss) and the effect of series resistance (R-s). These changes in the C-m and G(m)/w especially are found noticeable at low frequencies. The variation of the R-s and N-ss for the Sn/p-InP SBD obtained from C-m-V and G(m)/w-V characteristics using Nicollian and Goetzberger and Hill's methods, respectivelly. The distribution profile of R-s-V gives two peaks in the inversion and accumulation region, respectively, at low frequencies and these peaks disappear with increasing frequencies. Also, the energy-density distribution profile of interface states exponentially decreases with increasing frequency. Experimental results confirm that the values of N-ss and R-s of the Sn/pInP SBDs are important parameters which strongly influence the C-m-V and G(m)/w-V measurements.