An improved solvent and process for treating and separating acid gas, particularly hydrogen sulfide from gas mixtures containing the same, such as natural gas mixtures containing hydrogen sulfide, carbon dioxide and methane. The process involves the use of a solvent comprising a mixture of dimethyl ethers of polyethylene glycols to absorb the hydrogen sulfide and part of the carbon dioxide under superatmospheric pressure. The solvent containing dissolved hydrogen sulfide and carbon dioxide is flashed at reduced pressure to remove most of the carbon dioxide and produce a 'semilean' solvent. Part of the semilean solvent is recycled to an intermediate part of the absorber; the remaining semilean solvent containing hydrogen sulfide is subjected to an oxygen containing gas under conditions that result in complete removal of the hydrogen sulfide to produce a 'lean' solvent. The lean solvent is recycled to the top of the absorber. By the use of two solvent feeds to the absorber, the economy of the process is improved.