Substoichiometric tungsten oxides WO3-x, especially nanoscopic forms of W18O49, are promising materials due to their many exciting properties, resulting in potential applications in various technologies, like electrochromic devices, sensors, etc. W18O49 exhibits near-infrared absorption, which could be exploited for heat shielding, heat generation, and water evaporation closely connected to recently demonstrated water desalinization. The tungsten suboxides could also be used in the photoreduction of carbon dioxide, photocatalysis, electrocatalysis, and photoluminescence. The tungsten suboxides' characteristics, including their distorted inner structure, their highly oxygen-deficient structure, and their nanoscopic size, were examined in many studies. The structure containing triangular and hexagonal channels allows W18O49 to act as an anodic material for lithium-ion batteries. Intercalation of lithium ions into the W18O49 structure was studied for triggered lattice contraction, which result in macroscopic material flexibility and electrochromic color change. W18O49 was successfully exploited as a precursor in the large-scale synthesis of WS2 nanotubes. Another feature of this material is its sensory properties for NOx and ammonia gases. There are several different approaches to preparing nanoscopic W18O49 and other tungsten suboxides in nanowhisker or nanofibrous forms that differ from each other in a synthetic method or in a different tungsten-containing precursor. The most frequently used method is based on the solvothermal reaction of WCl6 or W(CO)6 with aliphatic alcohols in an autoclave or just at elevated temperature in high boiling point solvents. This route results in uniform nanowhiskers of various lengths and thicknesses. Other possible preparation procedures involve controlled oxidation of metallic tungsten with water vapor or flame synthesis based on the deposition of tungsten oxides on various surfaces by heating a tungsten mesh with a high-temperature heater. Tungsten disulfide WS2 could also be used as a tungsten source for these nanofibers using the high-temperature, low-pressure reactor in the presence of water vapor. This study was conducted in a chamber of an electron microscope with a heating extension serving as a sample holder. A similar study has been done based on the oxidation of tungsten filament to substoichiometric tungsten oxide whiskers with characterization and material properties testing performed entirely in-situ in the electron microscope chamber.