NOVELTY - Forming a conductive feature on a flexible substrate involves direct printing a precursor composition comprising metallic nanoparticles, a metal precursor compound to a metal and a liquid vehicle on the flexible substrate; and heating the precursor composition.    USE - For forming a conductive feature on a flexible substrate useful for fabricating e.g. electrode in a solar cell, flat panel display, transparent conductive feature e.g. indium tin oxide (ITO) and antimony tin oxide (ATO) (claimed) in display applications and as color tunable oxide layer in electrochromic applications. Also useful e.g. for providing connection between chips and other components in smart cards and RF tags; for fabricating microelectronic components e.g. multichip modules (particularly for prototype designs or low-volume production); for manufacturing flat panel displays e.g. electrodes for a plasma display panel, and field emission display; for manufacturing thin-film electroluminescent (TFEL) displays; for manufacturing inductor-based devices including transformers, power converters and phase shifters; for fabricating antennas e.g. antennas for cellular telephones; for fabricating transparent antennas for radio frequency (RF) tags and smart cards; for printing disposable electronics such as games included in magazines; for printing non-planar surface e.g. windshields, electronic components, electronic packaging and visors; for manufacturing nonlinear devices e.g. organic field effect transistors (OFET) or organic thin film transistors (OTFT); for application to inductor-based devices including transformers, power converters, phase shifters and low-temperature cofired ceramic package; for producing electronic circuit for making printed wiring board (PWBs) and printed circuit boards (PCBs); as underfill materials used below electronic chips to attach the chips to surfaces and other components; for manufacturing circuits imbedded in devices e.g. disposable light-emitting diodes, portable computers, pagers, cell phones and internet compatible devices e.g. personal organizers and web-enabled cellular phones; for security and authentication applications e.g. coupon redemption, inventory security, currency security, compact disk security and driver's, license and passport security; as alternative to magnetic strips in improving the security of credit cards and ATM cards; for screening electromagnetic radiation or earthing electric charges in making touch screens, radio frequency identification tags, electrochromic windows and in imaging systems e.g. silver halide photography or electrophotography.    ADVANTAGE - The process involves precursor compositions is of low viscosity is deposited on the substrate using direct-write methods such as ink-jet deposition. The precursor compositions have a low decomposition temperature that enables the formation of electronic features on a variety of substrates, including organic substrates. The precursor composition is deposited on the substrate and is reacted to form highly conductive electronic features having good electrical and mechanical properties. The precursor compositions have a wide range of properties and a wide range of relative cost (i.e. in high volume applications that do not require well-controlled properties, inexpensive precursor compositions can be deposited on cellulose-based materials such as paper to form simple disposable circuits). The method allow the formation of conductive features on a substrate, where the features have average width of the smallest dimension (i.e. a minimum feature size of not greater than 75 (preferably not greater than 50, especially not greater than 25) microns, and a thickness greater than 1 (preferably greater than 5) microns). The conductive features have high precision circuitry having good electrical properties (i.e. a conductivity that of not less than 10% the conductivity of the equivalent pure metal, and a resistivity of not greater than 4 (preferably 2) times the resistivity of the equivalent pure metal). The method requires relatively low processing temperatures (i.e. not greater than 300 (preferably not greater than 225, especially not greater than 185)degreesC to form the conductive feature on the substrate. The direct printing of low viscosity precursor compositions permits the formation of prototypes in a rapid and efficient manner in low production cost and reduces product development time compared to prior art paste techniques; allow low-volume production applications; and the deposited features formed have high resolution, high dimensional stability and high density. The composition allows the direct deposition of metal electrodes on low temperature substrates such as plastics with excellent adhesion and sheet resistivity values. Direct printing of conductive materials enable low cost manufacturing of large area flat displays. The precursor composition and printing methods do not generate any waste, are single step direct printing process and are compatible with small-batch and rapid turn around production runs. The precursor compositions enable the use of low cost deposition techniques, such as ink-jet printing, for depositing the components.