The velocity of money usually rises in expansions and falls in recessions. This paper explains this pro-cyclical movement of velocity using two ideas: (i) during business cycles the movement of investment and consumption of durable goods has a larger amplitude than consumption of non-durable goods and services; (ii) the velocity associated with expenditure on investment and durable consumption goods is much higher than the velocity associated with consumption of non-durable goods and services, because the former are synchronized with the attainment of money by economic agents whereas the latter are not. In this setting, the rise in the weight of expenditure in durable goods relative to the weight of non-durable goods and services, which occurs during expansions, generates an increase in the average velocity of circulation. The opposite happens during recessions and thus velocity moves pro-cyclically.