The main objective of this paper is to calculate an average value for an electricity tariff which will facilitate the introduction of high efficiency electric motors in Brazil and validate the argument that relatively low electricity tariffs are not a major obstacle to improved energy efficiency. Two Computational models are developed for technical-economic evaluation to assess economic attractiveness by calculating feasible average electricity tariffs in order to create a market for substitution of standard motors by new high efficiency models (purchase decision model), as well as to determine if retrofitting of standard installed motors by others with high efficiency characteristics is viable and, if so, to specify the optimum timing for such substitution (substitution decision model). The results indicate that with the current average tariffs of electricity in Brazil, high efficiency motors are economically attractive compared to standard motors. There is an obvious need for complementary instruments to assist massive market penetration of high efficiency electric motors in Brazil.