Analyzing powers and differential cross sections have been measured for elastic scattering of 22 MeV polarized protons from ⁴⁰Ca, ¹⁶O and ¹²C, and differential cross sections for inelastic scattering of 22 MeV protons from 3^-(3.736 MeV) and 5^-(4.491 MeV) states of ⁴⁰Ca have also been measured. The experimental data for polarized proton elastic scattering have been analyzed with a phenomenological optical potential parameters, the experimental data and theoretical values are in good agreement. In the theoretical frame of microscopic single scattering model, transition densities extracted from electron inelastic scattering and M3Y and Halderson's effective interactions have been utilized to analyze the experimental data of 22 MeV proton inelastic scattering from ⁴⁰Ca. Overall, it seems that Halderson's effective interaction can better describe the experimental data than M3Y although the degree of agreement between experimental and theoretical values needs to be improved.