The target of the proposal is the first experimental demonstration of attosecond coherent control of electron motion in many-particle systems. The past decade has seen remarkable advances in the field of coherent control of chemical reactions thanks to the application of femtosecond technology; I propose to use the emerging attosecond technology to achieve coherent control of photodissociation reactions on a purely electronic scale. I will mainly concentrate on molecules with biological interest. The success of the project will be based on the possibility to initiate and control the sub-femtosecond electronic motion in large molecules, by using high-intensity isolated attosecond pulses. Such electron motion precedes and determines the subsequent nuclear rearrangement, which ultimately leads to the chemical change. In this way it will be possible to control in a direct way the outcome of a chemical reaction, which is one of the central problems in modern chemistry. A crucial benchmark of the project, substantially beyond the current state-of-the-art in Attosecond Science, will be the experimental demonstration of attosecond pump / attosecond-probe measurements, which for the present are not technically feasible. Electron dynamics will be measured, with attosecond resolution, in many-particle systems, ranging from simple molecules to complex bio-molecules.The application of attosecond pulses and the development of attochemistry techniques for the investigation of the primary electronic steps of chemical processes, is a completely new and challenging research field, with tremendous prospects for both fundamental research and technology. In particular, the attosecond coherent control of charge localization in bio-molecules can offer unique information on the mechanisms at the basis of biological signal transmission or on the processes leading to damaging of complex biological molecules (from polypeptides to proteins and DNA).