A catalyst-free, solution-phase synthesis method for cesium lead halide perovskite nanowires (CsPbX3 NWs) is reported. These NWs are single crystalline with uniform growth direction and crystallize in the orthorhombic phase. Both CsPbBr3 and CsPbI3 are photoluminescence (PL) active, with composition-dependent temperature and self-trapping behavior. These NWs with a well-defined morphology could serve as an ideal platform for the investigation of fundamental properties and the development of future applications in nanoscale optoelectronic devices based on all-inorganic perovskites. The synthesis of CsPbX3 NWs was performed under air-free conditions using standard Schlenk techniques, by reacting Cs-oleate with Pb-halide in the presence of oleic acid and oleylamine in octadecene (ODE) at 150-250 °C. The reaction dynamics were studied at 150 °C, revealing the formation of nanocubes, thin NWs, and square-shaped nanosheets. The growth of CsPbI3 NWs requires elevated temperatures (T > 180 °C) and demonstrates much faster kinetics. The reaction is less controllable and the size distribution of the NWs is wider, ranging from tens to hundreds of nanometers. Structural characterization of CsPbX3 NWs shows that they crystallize in the orthorhombic phase. The optical properties of CsPbX3 NWs were studied by measuring the UV-Vis absorption and PL spectra. The absorption onsets for CsPbBr3 and CsPbI3 NWs were found to be 521 nm (2.38 eV) and 457 nm (2.71 eV), respectively. The narrow PL spectrum of CsPbBr3 corresponds to excitonic emission with a small degree of quantum confinement. The PL spectrum of CsPbI3 consists of two distinct peaks, with the narrow, high-energy peak likely stemming from excitonic emission and the broad, low-energy peak attributed to the formation of self-trapped excitons (STE). The optical properties of CsPbX3 NWs show that both CsPbBr3 and CsPbI3 are PL active, and exhibit both unique compositional and temperature-dependent behavior. Future studies with these NWs will concentrate on the investigation of their electronic and thermoelectronic properties as well as the development of their optoelectronic applications. Additionally, while this work focuses on the CsPbX3 class of compounds, the synthetic method reported here can potentially be applied to other inorganic perovskites, such as tin-based perovskites, which will be less toxic.A catalyst-free, solution-phase synthesis method for cesium lead halide perovskite nanowires (CsPbX3 NWs) is reported. These NWs are single crystalline with uniform growth direction and crystallize in the orthorhombic phase. Both CsPbBr3 and CsPbI3 are photoluminescence (PL) active, with composition-dependent temperature and self-trapping behavior. These NWs with a well-defined morphology could serve as an ideal platform for the investigation of fundamental properties and the development of future applications in nanoscale optoelectronic devices based on all-inorganic perovskites. The synthesis of CsPbX3 NWs was performed under air-free conditions using standard Schlenk techniques, by reacting Cs-oleate with Pb-halide in the presence of oleic acid and oleylamine in octadecene (ODE) at 150-250 °C. The reaction dynamics were studied at 150 °C, revealing the formation of nanocubes, thin NWs, and square-shaped nanosheets. The growth of CsPbI3 NWs requires elevated temperatures (T > 180 °C) and demonstrates much faster kinetics. The reaction is less controllable and the size distribution of the NWs is wider, ranging from tens to hundreds of nanometers. Structural characterization of CsPbX3 NWs shows that they crystallize in the orthorhombic phase. The optical properties of CsPbX3 NWs were studied by measuring the UV-Vis absorption and PL spectra. The absorption onsets for CsPbBr3 and CsPbI3 NWs were found to be 521 nm (2.38 eV) and 457 nm (2.71 eV), respectively. The narrow PL spectrum of CsPbBr3 corresponds to excitonic emission with a small degree of quantum confinement. The PL spectrum of CsPbI3 consists of two distinct peaks, with the narrow, high-energy peak likely stemming from excitonic emission and the broad, low-energy peak attributed to the formation of self-trapped excitons (STE). The optical properties of CsPbX3 NWs show that both CsPbBr3 and CsPbI3 are PL active, and exhibit both unique compositional and temperature-dependent behavior. Future studies with these NWs will concentrate on the investigation of their electronic and thermoelectronic properties as well as the development of their optoelectronic applications. Additionally, while this work focuses on the CsPbX3 class of compounds, the synthetic method reported here can potentially be applied to other inorganic perovskites, such as tin-based perovskites, which will be less toxic.