Abstract Iron is essential to plant development. However, its excess can provoke an increase in reactive oxygen species and oxidative stress in plants. The objective of this work was to verify the effects of high concentrations of iron on the oxidative stress of seeds and young plants of Cecropia hololeuca and Carica papaya. The species were submitted to concentrations of 0.045, 4 and 8mM of iron in the form of ferrous sulfate and FeEDTA. The experiments of germination and initial growth took place in a growth chamber, with temperature of 25ºC and 12h photoperiod. We performed the lipid peroxidation test by extraction and quantification of malonaldehyde and hydrogen peroxide. The application of iron did not cause a significant elevation in the contents of malonaldehyde and hydrogen peroxide in the germination of C. hololeuca and C. papaya. In the young plants, the hydrogen peroxide did not change in any of the treatments. However, it was possible to observe an expressive increase in malonaldehyde concentration in both species when exposed to FeEDTA 4 to 8mM. The results indicate a sensibility of C. hololeuca and C. papaya to high iron levels, amplifying the oxidative stress process that can harm their growth and initial development.