A new general relation for the size dependent charge-transfer-to-solvent (CTTS) energy of finite size solvated anionic clusters is derived based on a microscopic theory with unknown interaction potential. It is shown that the new extrapolation formula, when fitted to finite-size cluster data, yields significantly more accurate results for bulk CTTS energies of X NBH2O (X = I, Br and Cl) systems (within 3% w. r. t. experimentally measured ones). Based on linear correlation between vertical detachment energy with CTTS energy, present theory provides a route to calculate size dependent CTTS energy from the knowledge of vertical detachment energy or vice versa. (C) 2011 Elsevier B. V. All rights reserved.