In this thesis, the synthesis of nanosized transition metal oxides, which exhibit pseudocapacitive charge storage in Li-ion and Na-ion chemistries, is explored via a "green" continuous hydrothermal flow synthesis (CHFS) process. The materials are characterised, and their electrochemical properties evaluated, as active materials in anodes for Li-ion batteries (LIBs), Na-ion batteries (NIBs), Li-ion hybrid electrochemical capacitors (Li-HECs), and Na-ion hybrid electrochemical capacitors (Na-HECs). Chapter 1 gives a background on electrochemical energy storage, including a description of different active materials for energy storage devices. In Chapter 2, the experimental methods and materials employed are discussed. Chapters 3 and 4 explore how doping an insertion material such as TiO2 (anatase) with molybdenum, vanadium, and niobium can improve electrochemical performance and which synergistic and antagonistic effects can be achieved by co doping. The role of pre-lithiation/sodiation on the performance of Li-HECs and Na HECs, respectively, is explored in Section 3.4.2.3. In Chapter 5, the co-precipitation of conversion active materials (MoO2, NiCo2O4) with TiO2 is explored and the benefits of the inclusion of the more stable TiO2 (anatase) phase on cycling stability and rate performance in LIB anodes is discussed. Chapter 6 explores how mixed molybdenum/vanadium oxides can provide a route to high power and high energy active materials for LIBs by highly pseudocapacitive charge storage, which is faster than diffusion-limited charge storage.