Electronic version of an essay based on literature review and preliminary data regarding the use of redox poised (buffered) solutions for verification and calibration of electrodes used to measure oxidation-reduction potential (ORP) of environmental samples. The essay was written in 1985, submitted as a critical mini-review to an environmental science journal, but was rejected on grounds that ORP measurements were hopelessly unreliable. No further effort was made to publish the essay, but at times during the 35 years since 1985, we have found the document to be a useful reference. The document is provided here in the originally submitted form—after scanning to a PDF with OCR—without any updates to the content.