The absolute absorption cross sections for photoexcitation of D2 to N=0N=0 Rydberg levels have been measured at a resolution of 0.001 nm in the 123500 - 135000 cm−1 spectral range. The experimental energies and line intensities are compared with ab initio multichannel quantum defect (MQDT) calculations of the n⩾4n⩾4View the MathML sourcenpσ1Σu+N=0N=0 levels of D2. The calculations provide theoretical values of level positions, line intensities and autoionization widths. They are based on quantum-mechanical clamped-nuclei potential energy curves and dipole transition moments available for the lowest Rydberg members of the npσnpσ series. The overall agreement between experiment and theory is good. The decay dynamics of the excited N=0N=0 Rydberg levels is discussed based on the observed quantum yields for ionization, dissociation and fluorescence, and is compared with the yields previously observed in the analogous states of the H2 isotopomer.