Abstract Volcanic rocks in Thailand are widely distributed in both time and space, although most occur in a broad swathe that extends from Northern to SE Thailand (Figs 15.1 & 15.2 ). They range in age from Carboniferous (and older) to Late Cenozoic, and have been key components in developing tectonic models for Thailand and for SE Asia as a whole (e.g. Bunopas & Vella 1978 , 1983 , 1992 ; Hutchison 1989 ; Barr & Macdonald 1991 ; Yang et al. 1994 ; Metcalfe 1996 , 1997 , 2002 ; Charusiri et al. 1997 , 2002; Hada et al. 1999 ; Sone & Metcalfe 2008 ). Palaeozoic and Mesozoic volcanic rocks (Fig. 15.1 ) occur mainly in association with zones of deformed Palaeozoic and Mesozoic rocks generally referred to as the Sukhothai and Phetchabun fold belts (e.g. Bunopas 1981 ; Wielchowsky & Young 1985 ; Hahn et al. 1986). In contrast, Cenozoic volcanic rocks are more broadly distributed (Fig. 15.2 ). The aim of this chapter is to summarize the available infor mation about these volcanic rocks and to highlight where uncer tainties exist. We build on earlier compilations such as those of Thanasuthipitak (1978a) , Vichit et al. (1978) , Panjasawatwong & Yaowanoiyothin (1983) and Jungyusuk & Khositanont (1992) . Key information is summarized in tables that attempt to include all volcanic and volcaniclastic units,