Meson-baryon effective chiral Lagrangians at order $p^4$

We construct the three-flavor Lorentz-invariant meson-baryon chiral Lagrangians at the order $p^4$, with which a full one-loop investigation may be performed. One obtains 540 independent terms. The processes with the minimal number of mesons and photons to which this order of Lagrangians may contribute are also presented.