Quasi-two-dimensional hole gas in strained Si/SixGe1-x/Si quantum well structure is investigated both theoretically and experimentally. The hole effective mass and the charge distribution in the structure are obtained from the self-consistent solution of the Schrodinger-Poisson equations. The calculation results show the dependence of the averaged mass on the measurement temperature and the averaged mass of 0.20 m(0) at T = 4 K. High quality Si/Si0.8Ge0.2/Si p-type modulation-doped quantum well is grown by molecular beam epitaxy and the electrical properties measured. Hall mobility as high as similar to 10,400 cm(2)/V . s with a sheet carrier concentration of similar to 1.1 x 10(12) cm(-2) and an effective mass of similar to 0.30 m(0) is obtained at T = 4 K.