The recombination lifetimes for the radial and angular quantum number conserved 1S–1Sand 1P–1Ptransitions from three‐dimensionally confined electrons in CdSxSe1−xwere measured by time‐resolved photoluminescence (PL). The assignment of the observed transitions was supported by calculations of eigen energy levels and squared matrix element ratio for these transitions as well as well‐resolved PL peaks arising from 1S–1Sand 1P–1Ptransitions.