The partial hydrogenation of 1,3-dienes is a structure sensitive reaction that is typically catalysed by classical heterogeneous (heterotopic) or homogeneous (homotopic) catalysts. Recently, soluble transition-metal nanoparticles (M-NPs), particularly palladium and gold-based systems, have emerged as an efficient alternative. Here, we review the current state of the techniques for the partial hydrogenation of 1,3-dienes by M-NPs and conclude that, from the reactivity point of view, these materials possess heterotopic-like and homotopic-like characteristics. They are heterotopic-like because the relative concentration of the monoalkene with respect to the diene does not affect the product selectivity and their catalytic performance is affected by their physical properties (such as size and shape). Furthermore, they are easily recoverable, with long catalytic lifetimes. Additionally, as homotopic systems, their reactivity can be tuned by using an appropriate organic stabiliser, which displays substrate-selective levels that are not observed for classical heterotopic catalysts.