Kemia ya fizikia (kwa Kiingereza: Physical chemistry) ni tawi la kemia ambalo linashughulikia kuchunguza tabia za kifizikia za dutu, k.mf. shinikizo, ujazo, joto la gesi fulani. Msamiati "physical chemistry" ulitungwa na Mikhail Lomonosov mwaka 1752, alipotoa kozi iliyoitwa "A Course in True Physical Chemistry" (Russian: «Курс истинной физической химии») kwa wanafunzi wa Chuo Kikuu cha Petersburg. Alexander Vucinich (1963). Science in Russian culture. Stanford University Press, 388. ISBN 0-8047-0738-3.  In the preamble to these lectures he gives the definition: "Physical chemistry is the science that must explain under provisions of physical experiments the reason for what is happening in complex bodies through chemical operations".