This disclosure describes multi-fluid kits for three-dimensional printing, three-dimensional printing kits, and systems for three-dimensional printing. In one example, a multi-fluid kit for three-dimensional printing can include a fusing agent and a detailing agent. The fusing agent can include water and metal oxide nanoparticles dispersed therein. The metal oxide nanoparticles can be selected from titanium dioxide, zinc oxide, cerium oxide, indium tin oxide, or a combination thereof. The metal oxide nanoparticles can have an average particle size from about 2 nm to about 500 nm. The detailing agent can include a detailing compound.