Rb-H2 mixture was irradiated with pulses of 696.4 nm radiation from a OPO laser, populating 6D state by two-photon absorption. The vibrational levels of RbH(Х 1Σ+,ν″=0～2) generated in the reaction of Rb(6D) with H2. Vibrational-state-specific total-removal relaxation rate coefficients, kν(M), for RbH(Х 1Σ+,ν″=15～22) by M=H2 and N2 were investigated in a pump and probe configuration. By the overtone pumping with a cw diode laser, highly vibrational states ν″=15～22 of RbH in its ground electronic state were obtained. Another diode laser was used to probe the prepared vibrational state. The decay signal of laser induced time-resolved fluorescence from A 1Σ+(ν′)→Х 1Σ+(ν″) transition was monitored. Based on the Stern-Volmer equation, the total relaxation rate coefficient kν(H2) were yielded. A plot of kν(H2+N2) vs α(mole fraction H2) yields a line with a slope of kν(H2)-kν(N2) and an intercept of kν(N2). The values of kν(H2) obtained from the slope of the fitted lines compare well with determined values of the kν(H2) from the Sern-Volmer plots. At ν″<18, the rate coefficients kν(M) increases linearly with vibrational quantum number. This linear region is dominated by single quantum relaxation (Δν=1) collisional propensity rules. The region (ν″≥18) where the dependence is much stronger than linear shows significant contribution from multiquantum (Δν≥2) relaxation or resonant vibration-vibration energy transfer between highly vibrationally excited RbH and H2 or N2. For RbH(ν″)+N2(0), we measured the time-profile of ν″=16 after preparation of ν″=21. A clear bimodal distribution was observed. The first peak is due to resonant vibration-vibration energy transfer: RbH(ν″=21)+N2(0)→RbH(ν″=16)+N2(1). The much broader second peak, at longer time delays, is due to sequential single-quantum relaxation. Although the second process results in a distribution that is much more spread out in time, the peak height is in the same order of magnitude, indicating that the two processes are at least comparable in probability.