Actinyls AnO(2) with An = U, Np, and Pu in an expanded porphyrin, alaskaphyrin (AP), are studied by a relativistic density-functional method. The electronic structures of both AnO(2) and AnO(2)AP are investigated by considering all possible low-lying states. To examine the importance of relativity, nonrelativistic calculations were also performed. For UO2 and NpO2, the ground state is altered by the relativistic effects, but it remains unchanged for PuO2. The nonrelativistic ground states of the AnO(2)AP complexes are all high spin, where the AP highest occupied molecular orbital, b(2g) is singly occupied. At the relativistic level, there are two electrons in b(2g). The bonding characteristics in AnO(2)AP are examined by calculations of the AnO(2)-AP binding energy and charge distribution on AnO(2). Other properties such as ionization potentials and electron affinities are also calculated. The predicted spectroscopic constants for NpO2, PuO2, NpO(2)AP, and PuO(2)AP would aid in future spectroscopic studies of these molecules.