Lignocellulosic biomass is an alternate and renewable source of carbon. However, due to high oxygen content and diverse functionality, its conversion to fuels and chemicals is technologically challenging. Since physico-chemical characteristics of biomass and its derived components are very different from petroleum, fundamental understanding of their interactions with catalysts and solvents and of their behavior during thermochemical processing needs to be developed. in the present paper, we provide a perspective on how multiscale molecular modeling can assist in developing the science of biomass processing. The scope of this paper is limited to liquid phase catalytic and pyrolytic conversion of biomass. Car-Parrinello molecular dynamics (CPMD), a multiscale method that combines quantum mechanics and classical molecular dynamics and is an excellent choice to simulate biomass interactions in the condensed phase, is discussed. An overview of metadynamics, a method to accelerate CPMD dynamics, is also given. Revealing the chemistry of biomass pyrolysis, identifying liquid phase catalytic reaction mechanisms and developing a fundamental understanding of the role of solvents in biomass processing are the three main areas highlighted in this paper. Molecular modeling based investigations in these areas are reviewed and key findings are summarized. Limitations of the current approaches are discussed and the relevance of multiscale methods like CPMD and metadynamics is discussed. Potential studies that could implement multiscale molecular modeling methods to solve some of the challenging problems in developing biomass conversion technology are elaborated and an outlook is provided. (C) 2014 Elsevier Ltd. All rights reserved.