A series of polynuclear superalkali cations YLi(3)(+) (Y = O(2), CO(4), C(2)O(4), and C(2)O(6)) have been studied using ab initio method. The structural characters and stabilities of these systems are found to be related to the nature of the central cores. In the lowest-energy structure of the C(2)O(4)Li(3)(+) cations, the central group features a slight distortion. While in the global minima of O(2)Li(3)(+), CO(4)Li(3)(+) and C(2)O(6)Li(3)(+) cations, the central cores are divided into various units including one peroxo group (O(2)). These YLi(3)(+) (Y = O(2), CO(4), C(2)O(4), and C(2)O(6)) species exhibit very low vertical electron affinities of 3.01-3.85 eV (except one outlier in one of the O(2)Li(3)(+) species which lie much higher in energy than the most stable structure) and hence should be classified as superalkali cations, and the corresponding neutral species can be regarded as superalkalies. Such polynuclear superalkalies are candidates to the superatoms and offered potential building blocks for the assembly of new materials in which strong electron donors are involved.