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<p>In this work we present airborne in situ trace gas observations of hydrogen peroxide (H<span class="inline-formula">₂</span>O<span class="inline-formula">₂</span>) and the sum of organic hydroperoxides over Europe during the Chemistry of the Atmosphere – Field Experiments in Europe (CAFE-EU, also known as BLUESKY) aircraft campaign using a wet chemical monitoring system, the HYdrogen Peroxide and Higher Organic Peroxide (HYPHOP) monitor. The campaign took place in May–June 2020 over central and southern Europe with two additional flights dedicated to the North Atlantic flight corridor. Airborne measurements were performed on the High Altitude and LOng-range (HALO) research operating out of Oberpfaffenhofen (southern Germany). We report average mixing ratios for H<span class="inline-formula">₂</span>O<span class="inline-formula">₂</span> of 0.32 <span class="inline-formula">±</span> 0.25, 0.39 <span class="inline-formula">±</span> 0.23 and 0.38 <span class="inline-formula">±</span> 0.21 ppb<span class="inline-formula">_v</span> in the upper and middle troposphere and the boundary layer over Europe, respectively. Vertical profiles of measured H<span class="inline-formula">₂</span>O<span class="inline-formula">₂</span> reveal a significant decrease, in particular above the boundary layer, contrary to previous observations, most likely due to cloud scavenging and subsequent rainout of soluble species. In general, the expected inverted C-shaped vertical trend with maximum hydrogen peroxide mixing ratios at 3–7 km was not found during BLUESKY. This deviates from observations during previous airborne studies over Europe, i.e., 1.64 <span class="inline-formula">±</span> 0.83 ppb<span class="inline-formula">_v</span> during the HOOVER campaign and 1.67 <span class="inline-formula">±</span> 0.97 ppb<span class="inline-formula">_v</span> during UTOPIHAN-ACT II/III. Simulations with the global chemistry–transport model EMAC partly reproduce the strong effect of rainout loss on the vertical profile of H<span class="inline-formula">₂</span>O<span class="inline-formula">₂</span>. A sensitivity study without H<span class="inline-formula">₂</span>O<span class="inline-formula">₂</span> scavenging performed using EMAC confirms the strong influence of clouds and precipitation scavenging on hydrogen peroxide concentrations. Differences between model simulations and observations are most likely due to difficulties in the simulation of wet scavenging processes due to the limited model resolution.</p>