Two-electron properties in momentum space for the atoms helium to neon have been calculated starting from explicitly correlated wave functions. The different integrals involved in the calculation have been evaluated by using the Monte Carlo algorithm. In particular, the spherically averaged interelectronic momentum distribution, gamma((2)) (p(12)), its radial moments [p(12)(n)], with n=-2 to +3, the expectation value [p(1) . p(2)], and both the electron-electron coalescence, gamma((2))(0), and counterbalance, Gamma((2))(0), densities have been calculated. A systematic study of the electronic correlation has been performed by comparing the correlated results with the corresponding Hartree-Fock ones. Finally an analysis of the structure of the interelectronic momentum distribution in terms of its parallel and antiparallel components has been carried out.