We have developed a series of new multi-coefficient electronic structure methods, MLSE(Cn)-DFT, that performed equally well on both neutral and charged systems. The lowest average mean unsigned error on 211 thermochemical kinetics data is 0.56 kcal/mol using the MLSE(C1)-M06-2X method. The simplified MLSE(C2)-M06-2X method can achieve similar accuracy at 54% of the computational cost. Therefore, it is the most recommended method. The highly simplified, but reasonably accurate, MLSE(C3)-B3LYP method is an economical alternative for larger systems. (C) 2009 Elsevier B.V. All rights reserved.