Five tronies (character studies) painted by Rembrandt and artists in his circle, which are or have been attributed to Rembrandt, from three collections were examined using complementary technologies. Dendrochronology of the panel of Head of a Bearded Man (c.1630, Oxford, Ashmolean Museum) connects it to paintings by both Rembrandt and Jan Lievens, while infrared reflectography revealed black underdrawn lines beneath the painted surface that suggest a spontaneous creative process at an early stage. Macro-X-ray fluorescence analysis (MA-XRF) of three paintings allowed conservators at the Mauritshuis (The Hague) to identify a copper-containing pigment in the midtones of the flesh (Portrait of Rembrandt with a Gorget, c.1629), differentiate original paint from later additions in the background (Tronie of an Old Man, c.1630–31), and determine where the ground was left exposed at the surface to act as shadows of the skin (Study of an Old Man, 1650). High-resolution digital microscopy of Head of an Old Man in a Cap (c.1630, Kingston, Canada, Queen’s University) revealed the order in which layers were applied, and visualised Rembrandt’s brushstrokes, paint handling and use of a tool to scratch into the wet paint. These technologies have developed or improved significantly since the Rembrandt Research Project published their research (1982–2015), advancing our technical knowledge about the five tronies.