Myosin is a molecular motor responsible for biological motions such as muscle contraction and intracellular cargo transport, for which it hydrolyzes adenosine 5'-triphosphate (ATP). Early steps of the mechanism by which myosin catalyzes ATP hydrolysis have been investigated, but still missing are the structure of the final ADP·inorganic phosphate (P i ) product and the complete pathway leading to it. Here, a comprehensive description of the catalytic strategy of myosin is formulated, based on combined quantumclassical molecular mechanics calculations. A full exploration of catalytic pathways was performed and a final product structure was found that is consistent with all experiments. Molecular movies of the relevant pathways show the different reorganizations of the H-bond network that lead to the final product, whose γ-phosphate is not in the previously reported HP γ O 4 2− state, but in the H 2 P γ O 4 − state. The simulations reveal that the catalytic strategy of myosin employs a three-pronged tactic: (i) Stabilization of the γ-phosphate of ATP in a dissociated metaphosphate (P γ O 3 − ) state. (ii) Polarization of the attacking water molecule, to abstract a proton from that water. (iii) Formation of multiple proton wires in the active site, for efficient transfer of the abstracted proton to various product precursors. The specific role played in this strategy by each of the three loops enclosing ATP is identified unambiguously. It explains how the precise timing of the ATPase activation during the force generating cycle is achieved in myosin. The catalytic strategy described here for myosin is likely to be very similar in most nucleotide hydrolyzing enzymes.T he molecular motor myosin cyclically interacts with the actin filament to generate the mechanical force that is used in living cells to achieve muscle contraction (1), cytokinesis (2, 3), and intracellular cargo transport (4). Hydrolysis of one ATP molecule per cycle provides the free energy that drives the actomyosin interaction cycle, as originally described by Lymn and Taylor (5). ATP is the common energy currency in biology, and is extremely stable in aqueous solution (6, 7). ATPases, the enzymes that catalyze the hydrolysis of the P β -O-P γ anhydride linkage in ATP, are ubiquitous in biology because they are needed to accelerate the release of free energy stored in ATP. Myosin manages to speed up the hydrolysis by a factor of 10 7 over the uncatalyzed rate in solution. The experimental uncatalyzed energy barrier is 29 kcal mol −1 (7,8), and the catalyzed barrier has been determined experimentally between 14.4 kcal mol −1 (9) and 14.8 kcal mol −1 (10). Understanding how myosin achieves its ATPase function is necessary to understand how myosin works as a motor, but also helps one to understand the functioning of the multitude of other nucleotide hydrolyzing enzymes. The catalytic mechanism of ATP hydrolysis in myosin has been studied extensively with methods such as protein crystallography (11)(12)(13)(14), mutagenesis (15, 16), photochemical kinet...