The dissolved oxygen concentration (DOC) in seawater injection systems is typically maintained near 10 to 20 ppb. However, these systems can experience DOC excursions that temporarily rise into the 100 to 1000 ppb range. The use of carbon steel piping in some systems is known to result in elevated corrosion rates during upset periods in which DOC increases. However, the particles that are generated from corrosion products during upset conditions are not well characterized or understood. The importance of understanding corrosion-generated particles relates to the plugging of the injection lines, which can lead to costly work-overs of the injection well. The main objective of this work is to examine the impact of DOC excursions on steel corrosion and iron-based particulates that form as a result of corrosion. A rotating cylinder electrode (RCE) electrochemical setup was implemented in conjunction with a particle analyzer instrument to make these correlations in real-time under controlled hydrodynamic conditions. Dissolved oxygen and pH were also continuously monitored throughout the tests. All testing was performed in a seawater simulant brine at 32°C. The key findings from the testing can be summarized accordingly: (1) particle sizes in the 20 to 30 µm range tended to concentrate when the DOC was raised to 1000 ppb; (2) localized corrosion was able to develop on the steel electrodes due to breakdown of a semi-protective film that formed over time; (3) DOC excursions may lead to irreversible increases in the baseline corrosion rate after dissolved oxygen is reduced back to low levels (e.g., 20 ppb).