We report accurate Ab initio studies of dipole polarizabilities and the first static hyperpolarizabilities (β) of polyacetylene with a number of substituents at the end part of the linear system. Geometries of all molecules were optimized at the Hartree–Fock level with the 6-311G++(d,p) basis set. The results indicate that for the NO2-П-Y systems we find group polarizabilities in the order N(Et)2>NBr2>N(Me)2>NHMe>PH2>NHNH2>SH>Br∼BH2∼CHO∼NHOH∼NH2>CN∼CH3∼Cl>NF2∼OCH3∼OH>H∼F. The study reveals inverse relationship between the Egap and first static hyperpolarizabilities. Compounds with the N(Et)2, NHNH2, N(Me)2, NHMe, NHOH, NH2 and OH end parts have large β values. A poor agreement results between the Ab initio and the AM1 values which give a correlation coefficient of 0.88.