A mass spectrometer employing a cycloidal‐focusing mass resolving system is described. The mass analyzer proper, including the magnet and a high‐speed continuous‐flow inlet system, weighs approximately seventy pounds. The resolving system shows good mass resolving power, sensitivity, and analytical accuracy up to about mass 150 amu, and adequate service life. The mass resolving power can be extended substantially in cases where some loss of sensitivity and analytical accuracy is tolerable.