The chemical microstructure of acrylonitrile-pentyl methacrylate (A-P) copolymers prepared by photopolymerization using uranyl ion as the photo sensitizer is analyzed by C-13 { H-1 } nuclear magnetic resonance spectroscopy. The composition of the copolymers were determined by elemental analysis, and comonomer reactivity ratios were determined by the Kelen-Tudos (KT) and the error in variable (EVM) methods. The terminal model reactivity ratios obtained from the EVM method are r(A) = 0.20 and r(P) = 2.62. The complete spectral assignment of the overlapping proton and carbon spectra of these copolymers were done with the help of distortionless enhancement by polarization transfer and two-dimensional H-1-C-13 heteronuclear shift correlation (inverse HETCOR) spectroscopy. The assignment of the various conformational and configurational sequences in the proton spectrum were made possible by two-dimensional correlated spectroscopy and total correlation spectroscopy experiments. Monte Carlo simulation was used to study the effect of the degree of polymerization on the triad fractions.