Previous kinetic data for the uncatalyzed evolution of oxygen from purified alkaline NaClO solutions have been extended to wider ranges of temperature and ionic strength, using a newly-reported unitized gas buret apparatus for determination of oxygen rates. Revised activation parameters for oxygen evolution are E(a) = 135300 - 4300 mu +/- 2000 J g . mol(-1) (Delta H-double dagger = E(a) - RT) and Delta S-double dagger = 9.8 - 9.2 mu +/- 6.1 J K(-1)g . mol(-1), respectively, at 40-70 degrees C and ionic strength mu = 1.5-5.5, valid also at 30 degrees C and mu = 4.2-5.5. Uncatalyzed rate constants k(0) calculated from these parameters can be used with the previously-derived integrated rate equation to predict amounts of oxygen that would be evolved from purified NaClO solutions under arbitrary conditions within the range investigated.