[en] Effect of cluster environment on the electron attachment to 2-nitrophenol (2NP) isstudied in homogeneous 2NP clusters and heterogeneous clusters of 2NP, argon and water.The cluster environment significantly reduces fragmentation of 2NP after electronattachment. Parent cluster anions 2NP_n^- are primary reactionproducts in both, homogeneous and heterogeneous clusters. Non-dissociative electronattachment to homogeneous clusters proceeds at low energies <2 eV, presumably via dipole-supportedstates. In heterogeneous clusters, the interaction with low energy (<2 eV) electrons is shielded by thesolvent. Surprisingly, the energetic threshold for the electron attachment rises with thenumber (n) of2NP molecules in the cluster (2NP)_n^-. This rise can be either due toa strong change of the 2NP conformation induced by the cluster environment or due to thethe competition with electron autodetachment after proton transfer that has been firstobserved by Allan in the formic acid dimer [M. Allan, Phys. Rev. Lett. 98,123201 (2007)]. We observe the same threshold rise for complex Ar_m·(2NP)_n^- andH₂O·(2NP)_n^- anions. This indicates that theelectron attachment to 2-nitrophenol in cluster environment is more influenced by thesolute − solute interactioncompared to the solute − solvent interaction. Graphical abstract: .