A new method for measuring neutron thermalizaton parameters that was proposed on theoretical grounds is tested experimentally for H2O. The characteristic thermalization parameters in the present formulation are where are Laguerre polynomials of order unity and degree i and T is the temperature of the system expressed in energy units. The present experimental results for H2O can be described using one parameter. The result is γ11 = (0.210 ± 0.026)cm-1 for 23 C. The value of this parameter as derived from diffusion-cooling measurements lies in the range of 0.4cm-1 to 0.8cm-1. A possible explanation for this discrepancy is given. The value of γ11 as calculated on the basis of Nelkin's model is about four times higher than the present result.