The experimental investigations on Q-switching of a ruby laser system by cryptocyanine are reported: 1) The dependence of output characteristics on dye concentration and other parameters of the laser cavity, 2) the dependence of output energy on temperature and solvent of the dye, 3) the influences of temperature, solvent and impurity content on the optical bleaching of the dye solution. Theoretical analysis and numerical tests are made for the third problem on the basis of the experiments.