Half-value thickness of aluminum absorbers has been investigated experimentally and theoretically. Cs-137, TI-204 and Sr-90/Y-90 radio-isotopes were used as beta sources. Inconsistency between experimental measurements and standard theoretical calculations has been removed with the help of fractional calculus. The experimental and theoretical half-thickness values have been found equivalent for fractional derivative order approximate to 0.3. (C) 2013 Elsevier Ltd. All rights reserved.