The NA48/2 experiment at CERN reports the first observation of the K->pi0e+e-decay from an exposure of 1.7x10^11 charged kaon decays recorded in 2003-2004. A sample of 4919candidates with 4.9% background contamination allows the determination of the branching ratioin the full kinematic region. The study of the kinematic space shows evidence for a structuredependent contribution in agreement with predictions based on chiral perturbation theory. Several P- and CP-violating asymmetries are also evaluated. The most precise measurement of the charged kaon semi-leptonic form factors obtained by NA48/2 with 4.4 million Ke3 and 2.3 million Km3 events collected in 2004 will also be presented.