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In work [1] ("Temperature dependence of ultracold neutron loss rates"E.Korobkina et al., PRB 70,035409) results of measurement of temperaturedependence of losses of ultracold neutrons (UCN) in a range from 4 K to 300 Kat UCN storage in a copper trap are presented. At interpretation ofexperimental data it was artificially considered only the difference of lossesrate 1/tau(T)= 1/tau_exp(T)- 1/tau_exp(10K), (tau - UCN storage time in thetrap). It has been accepted for temperature dependence of losses which changesfrom 0 to 3.3*10-4 per one collision of UCN with a trap surface. However, theanalysis of raw experimental data shows that in a trap at temperature 10 Kthere is losses 1.0*10-3 per collision. They are considerably (in 3 times) morethan discussed temperature dependence and almost 10 times more than losses dueto capture cross section on copper. It is the most probable that these lossesare connected with leakage of UCN through a slit of trap shutter. Change of thesize of a slits on 25% at change of temperature from 300K to 10K can quiteexplain discussed temperature dependence. Certainly, hydrogen is present on asurface, but as it was shown at work [2] (V.P.Alfimenkov et al., JETP., Vol.55, No. 2 25 Jan.1992) temperature dependence in 3 times lower, even on theundegased surfaces than on the degassed and deuterated surface in work [1]. Atlast, deuteration of a trap surface allows almost completely to suppresstemperature dependence connected with presence of hydrogen [2]. The conclusionof work [1] is that hydrogen is localized on a surface in the form of a film,instead of distribution in the surface substance. This conclusion contradictsresults of measurement of energy dependence of UCN losses in work [2]. Moredetailed analysis of work [1] and works [2] is presented below.

Comment to the article "Temperature dependence of ultracold neutron loss rates" E.Korobkina et al., PRB 70,035409