In the neoclassical production theory technical change (TC) is specified as a function of time. However, some exogenous external factors other than time can also affect the rate of TC. In this paper, we model TC via a combination of time trend (purely non-economic) and other observable exogenous factors that shift the technology. The exogenous economic factors are used to define several technology indices. These technology indices are embedded into the production function in a flexible manner. By estimating this generalized production function, we get estimates of rate of TC which is decomposed into a pure time component as well as several components attributed to technology indices. The empirical model uses panel data on OECD, accession and enhanced engagement countries observed during 1980-2006. ©2013 Taylor & Francis.