Different transition metal ions with 3d unfilled shells are used for applications in solid state lasers and phosphors. Among the whole 3d group the ions with the 3d3 configuration are of particular importance, due to their specific energy level scheme, which can lead to three kinds of photoluminescence spectra: i) sharp spin-forbidden 2E→4A2 emission; ii) broad spin-allowed 4T2→4A2 emission; iii) coexistence of both these emissions.In the present work we review recent progress in the development of crystalline materials doped with the Mn4+ and Cr3+ ions.The Mn4+ ions-doped hosts exhibit only sharp emission spectra in the range from 620 nm to ~700 nm, depending on the host [1]. The phosphors with emission between 620 nm and 650 nm (such as K2SiF6, Na2SiF6 etc) are suitable for applications in white LEDs to produce warm white light. The phosphors emitting at longer wave lengths (e.g. double perovskites Ba2LaNbO6, La2LiSbO6 etc) are used for applications in white LEDs for agriculture, to enhance plant growth [2].In addition to several examples of tuning emission peak position by chemical composition, an important issue of dependence of the emission intensity on the local symmetry will be discussed in detail.The Cr3+ ions can produce all three above-mentioned spectra, depending on the host material. For example, in ZnAl2O4 and MgAl2O4 sharp Cr3+ red 2E→4A2 emission transition is peaked at around 685 nm [3], whereas in LaSc3(BO3)4 and (Ce,Gd)Sc3(BO3)4 crystals broad infrared Cr3+ 4T2→4A2 emission band is centered at 960 nm and 1100 nm, respectively [4, 5].An interplay of the strong and weak crystal field effects can produce redistribution of relative intensities of both 2E→4A2 and 4T2→4A2 emission transitions in the Cr3+-bearing phosphors. With increased temperature, the crystal field strength is decreased and the infrared 4T2→4A2 emission gains intensity. Ratio of intensities of these two transitions can be used for non-contact temperature measurements [6, 7]. Another potential application of such systems is pressure sensing. These examples justify recently renewed interest to the Cr3+ and Mn4+ ions.