Measured and calculated (without any adjustable material parameter) electron Hall mobility and carrier concentration in the range of 26.5-273 K are reported for a high-mobility free-standing bulk GaN grown by hydride vapor phase epitaxy. The peak electron mobility of 7386 cm(2)/V s at 48 K and a value of 1425 cm(2)/V s at 273 K were measured. An iterative solution of the Boltzmann equation was applied to calculate the mobility using the materials parameters either measured on the sample under study or recent values that are just becoming available with only the acceptor concentration being variable. Using only one donor and one conducting layer system, the donor and acceptor concentrations of 1.76 x 10(16) and 2.4 x 10(15) cm(-3), respectively, satisfy simultaneously the charge neutrality and electron mobility at all temperatures within the framework of the iterative method and measurements. The donor activation energy was determined to be 25.2 meV and is consistent with the value of about 30 meV for the hydrogenic ground state in a dilute semiconductor. The high electron mobility, low background impurity concentration, low compensation ratio, and negligible dislocation scattering demonstrate the high quality of the material studied.