The intermolecular interaction and microsolvation process of isomeric C 3H 3 + ions in molecular nitrogen are characterized by infrared (IR) photodissociation spectroscopy of C 3H 3 +–(N 2) n complexes ( n=1–6) and quantum chemical calculations ( n=0–4). The rovibrational analysis of the C 3H 3 +–N 2 spectrum unambiguously reveals the presence of (at least) two C 3H 3 + isomers in the ion source, namely the propargyl (H 2CCCH +) and the cyclopropenyl (c-C 3H 3 +) cations. Analysis of the cluster size-dependent vibrational frequency shifts and splittings, the photofragmentation branching ratios, and the results of density functional calculations provides a consistent picture of the microsolvation of c-C 3H 3 + and H 2CCCH + in inert nitrogen. In the most stable c-C 3H 3 +–(N 2) n complexes, the first three N 2 ligands form (nearly) linear and equivalent proton bonds to the three protons of c-C 3H 3 +, leading to highly symmetric planar structures with C 2v ( n=1, 2) and D 3h symmetry ( n=3). After completion of this first solvation subshell at n=3, further N 2 ligands form weaker intermolecular bonds to the C atoms of the nearly planar c-C 3H 3 +–(N 2) 3 ion core. The dissociation energies of the H-bonds and C-bonds in c-C 3H 3 +–(N 2) n are estimated as D 0(H)=900±130 cm −1 and D 0(C)=860±170 cm −1, respectively. In the most stable H 2CCCH +–N 2 complex, the N 2 ligand forms a linear ionic H-bond to the acetylenic CH group of H 2CCCH +, leading to a planar structure with C 2v symmetry. The calculations suggest that the next two ligands bind to the protons of the CH 2 group giving rise to planar structures with C s ( n=2) and C 2v symmetry ( n=3), and these structures are compatible with the observed IR spectra.