In order to probe electrolyte insertion in zeolites, we used our recent implementation of the Nonequilibrium Candidate Monte Carlo (NCMC) move in the osmotic ensemble with a relative probability set to 10 -3 . The starting configurations were the silicalite-1 and chabazite materials in equilibrium with a water reservoir at 400 and 200 MPa respectively, in which we will attempt to introduce ions pairs. Briefly, the osmotic ensemble is sampled using a hybrid Monte Carlo move using nonequilibrium molecular dynamics, or NCMC, initially proposed by Nilmeier 60 and later applied by Ross and co-workers to sample the distribution of NaCl electrolyte around biomolecules. We previously calculated the chemical potential of ion exchange ∆µ CnAm (P ) in the semi-grand canonical ensemble for "alchemically" transforming (n + m) water molecules chosen randomly into an electrolyte unit C n A m (where C m+ and A n-are the ionic species) in bulk electrolyte solution at fixed concentration. This chemical potential, used in combination with NCMC moves to insert or delete ions at constant number of particles in the system, defines the osmotic ensemble, where the fictitious reservoir is an electrolyte solution at a concentration imposed by the chemical potential. We tabulated this quantity in our previous work, and use here the values corresponding to molalities of 4.77 and 4.62 mol/kg for monovalent and divalent bulk electrolytes, respectively. The NCMC move consists of T = 200 steps, each one involving a perturbation of the system through interpolation of non-bonded parameters of the chosen molecules to be transformed, followed by relaxation with 200 MD steps with a timestep of 1 fs in the NVE ensemble. All simulations used a Nosé-Hoover thermostat, setting the temperature at 300 K. In addition, translations were performed both on ions and water while rotations were applied only to water molecules, in a ratio of 1:1:1. Simulation are performed until 1000 moves in the osmotic ensemble have been attempted.