Abstract Oxidative stress generated by hydrogen peroxide is faced by bacteria when encountering hostile environments. In order to define the physiological and regulatory networks controlling the oxidative stress response in the free-living bacterium Caulobacter crescentus , a whole transcriptome analysis of wild type and Δ oxyR strains in the presence of hydrogen peroxide for two different exposure times was carried out. The C. crescentus response to H 2 O 2 includes a decrease of the assimilative sulfate reduction and a shift in the amino acid synthesis pathways into favoring the synthesis of histidine. Moreover, the expression of genes encoding enzymes for the depolymerization of polyhydroxybutyrate was increased, and the RpoH-dependent genes were severely repressed. Based on the expression pattern and sequence analysis, we postulate that OxyR is probably directly required for the induction of three genes (katG , ahpCF). The putative binding of OxyR to the ahpC regulatory region could be responsible for the use of one of two alternative promoters in response to oxidative stress. Nevertheless, OxyR is required for the expression of 103 genes in response to H 2 O 2. Fur and part of its regulon were differentially expressed in response to hydrogen peroxide independently of OxyR. The non-coding RNA OsrA was upregulated in both strains, and an in silico analysis indicated that it may have a regulatory role. This work characterizes the physiological response to H 2 O 2 in C. crescentus , the regulatory networks and differentially regulated genes in oxidative stress and the participation of OxyR in this process. It is proposed that besides OxyR, a second layer of regulation may be achieved by a small regulatory RNA and other transcriptional regulators. Highlights • The C. crescentus response to H 2 O 2 was characterized by transcriptomics analysis. • OxyR is required for the expression of 103 genes in response to H 2 O 2. • Genes for assimilative sulfate reduction were downregulated in H 2 O 2 exposure. • Histidine biosynthesis genes were upregulated in H 2 O 2 exposure. • A non-coding RNA was upregulated upon H 2 O 2 exposure independently of OxyR [ABSTRACT FROM AUTHOR]