Excitation energies and transition probabilities for two electron one photon (Kαα) transition 2s22p6: 1S → 1s2 2s2p5: 1P have been estimated for the inner shell ionised atoms Ne, Na, Mg, Al, Si, P, S, Cl and Ar. Similar transition data have also been evaluated for Kααs transition 2s2p: 1P → 1s2: 1S of the highly stripped He like ions Ne8+, Na9+, Mg10+, Al11+, Si12+, P13+, S14+, Cl15+ and Ar16+. The branching ratio between the X-ray hypersatellite line Kα2h (2s22p6: 1S → 1s2s22p5: 1P) and Kαα line and that between Kα2h and Kααs transition has been estimated for all these ions. The method is based on variational principle with a correlated description of the initial and final states. Most of the data are new and agreement is very reasonable with the few available data.