The present invention is directed to compounds, compositions, methods, and kits for detecting reactive oxygen species (ROS) by conventional fluorescence microscopy, fluorescence spectroscopy, flow cytometry, and/or high content imaging. The compounds disclosed herein are novel reduced dyes, including Cy-based hydrocyanine dyes and Cy-based deuterocyanine dyes, which dyes are probes for detecting ROS and measuring oxidative stress in cells either in vitro and/or in vivo. Also described herein are processes for preparing novel reduced dyes, i.e., ROS probes, for use in the disclosed compositions, methods and kits.