  The NA48/2 Collaboration at CERN has accumulated unprecedented statistics of
rare kaon decays in the Ke4 modes: Ke4(+-) ($K^\pm \to \pi^+ \pi^- e^\pm \nu$)
and Ke4(00) ($K^\pm \to \pi^0 \pi^0 e^\pm \nu$) with nearly one percent
background contamination. The detailed study of form factors and branching
rates, based on these data, has been completed recently. The results brings new
inputs to low energy strong interactions description and tests of Chiral
Perturbation Theory (ChPT) and lattice QCD calculations. In particular, new
data support the ChPT prediction for a cusp in the $\pi^0\pi^0$ invariant mass
spectrum at the two charged pions threshold for Ke4(00) decay. New final
results from an analysis of about 400 $K^\pm \to \pi^\pm \gamma \gamma$ rare
decay candidates collected by the NA48/2 and NA62 experiments at CERN during
low intensity runs with minimum bias trigger configurations are presented. The
results include a model-independent decay rate measurement and fits to ChPT
description.
