In this talk we compare particle characteristics after their passage through 3D current sheets for the conditions suitable for the heliosphere and the solar corona. The theoretical results are probed by observations of the solar wind particles and magnetic filed variations measured during their crossing the sector boundary (midplane) of Heliospheric Current Sheet, current sheets in front of ICMEs and in solar corona leading to solar flares. We show that the measured in-situ particle characteristics during sector boundary crossings
(ion velocity, electron pitch angles and the distance at which electrons are turned from the HCS) are in close agreement with the 3D PIC simulations of particle acceleration in a reconnecting HCS with strong guiding field. We show the key parameters of solar wind particles observed at the leading edge of ICMEs (anti-correlation of ion and electron fluxes and appearance of bidirectional field-aligned energetic suprathermal electrons) can be also naturally explained by particle acceleration in 3D current sheets. The implications of these findings for particle acceleration in the solar flares are also discussed.