Satisfiability Problem is a great and competitive practical approach to solve a wide range of industrial and academic problems. The size and difficulty of the SAT instances have grown significantly over years thanks to solvers always more competitive. Among the recent solvers, the main part of them are sequential. Even if all of them include a very interesting innovation to improve performances, they can not take advantage of new multicore processors widely available today. To overcome this situation, MTSS (Multi-Threaded Sat Solver) allows to parallelize an existing sequential SAT solver by introducing the principle of guiding tree in shared memory.