Orthoptera, among the oldest and most numerous insect lineages, is an excellent model for evolutionary studies but has numerous taxonomic problems. To mitigate these issues, the cytochrome c oxidase subunit I (COI), standardized with the DNA barcode for Metazoa, is increasingly used for specimen identification and species delimitation. We tested the performance of COI as a DNA barcode in Orthoptera, using two analyses based on intra- and inter-specific distances, barcode gap, and Probability of Correct Identification (PCI); and estimated species richness through Automatic Barcode Gap Discovery (ABGD) and Assemble Species by Automatic Partitioning (ASAP). We filtered all sequences of Orthoptera available in Barcode of Life Data System (BOLD) and used 11605 COI sequences, covering 1132 species, 226 genera, and 18 families. The overall average PCI was 73.86%. For 82.2% of genera, the barcode gap boxplots were classified as "good" or "intermediate", indicating that COI can be effective as a DNA barcode in Orthoptera, although with varying efficiency depending on the need for more information. ABGD and ASAP inferred species richness similar to labels informed by BOLD for the suborders Caelifera and Ensifera. The representation of Orthoptera in the BOLD database and the results of these analyses are discussed.