Many advantages and applications of 2D codes and functional printing inks have led to the development of Smart Tags. Interactive 2D codes provide the ability to store a large number of various information on a relatively small area and are easy to use. Combined with temperature sensitive thermochromic inks, 2D codes can provide a possibility for making Smart Tags, which could be used in smart packaging applications. In this study, Smart Tag is a temperature – dependent system sensitive to surrounding temperature, which provides information in the form of 2D codes and hidden messages. By combining the information provided by the Smart Tag, it is possible to monitor the temperature conditions of a particular product, create anti – counterfeit elements, and high – temperature warning systems. In this paper, 2D codes will be printed using thermochromic (TC) inks with different activation temperatures (TA) in screen printing technique. Printed 2D codes will be exposed to the defined temperature range around TA, to determine readability of the codes by mobile code scanning. Colorimetric properties of TC inks will also be measured within the defined temperature range. The aim of this paper is to determine which temperature range of a particular TC ink provides readability of 2D codes. The results could help in design and development of 2D code - Smart Tags using functional inks. These kinds of Smart Tags could provide higher level of consumer protection, temperature monitoring of pharmaceutical and cosmetics products, as well as burn – hazard warning systems.