The microwave spectrum of 2-chloropropionitrile for 35Cl and 37Cl species has been studied for the first time from 10 to 40 GHz. A least-squares analysis of the observed a-, b-, and c-type transition frequencies give the rotational constants, quartic centrifugal distortion constants, and components of nuclear quadrupole coupling tensor in the principal axis system: A=5973.3196(104), B=3049.4864 (79), C=2147.1990 (66) MHz, Δ J =1.260(66), Δ JK =−2.12(14), Δ K =10.84 (30), δ J =0.383 (16) δ K =2.17(22) kHz, χ aa =−28.24(51) and χ bb −χ cc =−26.30(63) MHz for the 35Cl species; and A=5923.5952(118), B=2986.1587(98), C=2109.4657(68) MHz, Δ J =1.068 (75), Δ JK =−2.03(10), Δ K =10.53(38), δ J =0.404(10), Δ K =1.68 (15) kHz, χ aa =−23.41(93), χ bb −χ cc =−22.20(86) MHz for the 37Cl species. The molecular structures have been determined from these rotational constants and also from the ab initio calculation using the Gaussian 94 program at the MP2/6-31G ++ level. The experimental and calculated structural parameters are compared with those of other related molecules. The numerical value of the nuclear quadrupole coupling constants of chlorine for 2-chloropropionitrile are found to be higher and lower than those for 3-chloropropionitrile and chloroacetnitrile, respectively.