Recent results obtained by the COSY-11 collaboration concerning the product
ion of eta and eta ' mesons in the pp --> ppMeson reaction are presented. A
comparison of the production amplitude for the pi (0), eta and eta ' meson
s at the same phase space volume allows to conclude that the protonl-eta '
interaction is in the order of, or smaller than, the proton-pi (0) one. A t
otal cross section determined in a preliminary analysis of the data of elem
entary kaon and antikaon production via the pp --> pp K K+ (-) reaction mea
sured at excess of energy of Q = 17 MeV is reported.