Lasing characteristics of pyrromethene PM567 are investigated both theoretically and experimentally. It is established that the operating lifetime of solid-state active media based on PM567 in polymeric PMMA matrix can be significantly increased by proper purification of initial substances. It is demonstrated that addition of 8-MMAPOSS leads to an increase in the lasing efficiency; however, the operating lifetime in this case can decrease. Also, it is demonstrated using the XMCQDPT2 method that one of the main reasons for high lasing efficiency is the absence of S-1 -> S-n and T-1 -> T-n reabsorption at the lasing wavelength. (C) 2013 Elsevier B.V. All rights reserved.