Ab initio calculations in the framework of the density functional theory, with B3LYP functional, are performed to study the lowest-energy isomers of silicon sodium clusters SinNap(+) (n <= 6, p <= 2). The stability and the structural and electronic properties of neutral and positively charged systems are examined. The structure of SinNap keeps the frame of the corresponding Si-n cluster unchanged, and the electronic structure of SinNap is similar to that of the corresponding negative system SinP-. Adsorption energies, vertical and adiabatic ionization potentials, electric dipole moments, and static dipolar polarizabilities are calculated for each considered isomer.