  Context: In the laboratory, hydrogen peroxide (HOOH) was proven to be an
intermediate product in the solid-state reaction scheme that leads to the
formation of water on icy dust grains. When HOOH desorbs from the icy grains,
it can be detected in the gas phase. In combination with water detections, it
may provide additional information on the water reaction network. Hydrogen
peroxide has previously been found toward $\rho$ Oph A. However, further
searches for this molecule in other sources failed. Hydrogen peroxide plays a
fundamental role in the understanding of solid-state water formation and the
overall water reservoir in young stellar objects (YSOs). Without further HOOH
detections, it is difficult to assess and develop suitable chemical models that
properly take into account the formation of water on icy surfaces. Aims: The
objective of this work is to identify HOOH in YSOs and thereby constrain the
grain surface water formation hypothesis. Methods: Using an astrochemical model
based on previous work in combination with a physical model of YSOs, the
sources R CrA-IRS\,5A, NGCC1333-IRAS\,2A, L1551-IRS\,5, and L1544 were
identified as suitable candidates for an HOOH detection. Long integration times
on the APEX 12m and IRAM 30m telescopes were applied to search for HOOH
signatures in these sources. Results: None of the four sources under
investigation showed convincing spectral signatures of HOOH. The upper limit
for HOOH abundance based on the noise level at the frequency positions of this
molecule for the source R CrA-IRS\,5A was close to the predicted value. For
NGC1333-IRAS 2A, L1544, and L1551-IRS\,5, the model overestimated the hydrogen
peroxide abundances.
