A multichannel microspectrofluorometer based on an electron bombardment silicon camera tube, a multiscaling computer, and a miniature Amici prism for spectrometer, allows the scanning of the NAD(P)H fluorescence emission spectrum from a 30 &mgr; region in a single living EL2 ascites cancer cell, within 32 msec. Observations of changes in the relative maximum emission intensities of two fluorochromes within a same cell are quite possible (for emission maxima ∼ 10–20 nm apart). Thus, in the fluorescence emission spectrum of cells incubated with benzpyrene or dibenzanthracene, the 423 nm (polycyclic hydrocarbon)/443 nm [NAD(P)H] ratio is 1.25 or over, while it decreases to 1.0 or less upon microelectrophoretic addition of glucose‐6‐phosphate [NAD(P) reduction].