Abstract. Cross sections of the 144 Sm(n,α) 141 Nd and 66 Zn(n,α) 63 Ni reactions were measured at E n = 4.0, 5.0 and 6.0 MeV performed at the 4.5-MV Van de Graaff Accelerator of Peking University, China. A doublesection gridded ionization chamber was used to detect the alpha particles. The foil samples of 144 Sm 2 O 3 and enriched 66 Zn were placed at the common cathode plate of the chamber. Monoenergetic neutrons were produced by a deuterium gas target through the 2 H(d,n) 3 He reaction. The neutron flux was monitored by a BF 3 long counter. Cross sections of the 238 U(n,f) reaction were used as the standard to perform the (n,α) reaction measurement. Present results are compared with existing measurements and evaluations. They are generally in agreement with TALYS-1.6 code calculations. For the 144 Sm(n,α) 141 Nd reaction our measurements support the data of JEF-2.2. For the 66 Zn(n,α) 63 Ni reaction present results support the data of EAF-2010 and TENDL-2015 data.