The thermo-emf DV of the touching p-and n-type Cu/Bi-Te/Cu composites with different thicknesses of t(Bi-Te) and t(Cu) was measured as a function of time by alternating the temperature difference Delta T at periods of T = 20, 60, 120, 240 and infinity sec, where t(Bi-Te) was varied from 0.1 to 2.0 mm and t(Cu) from 0 to 4.0 mm. As a result, Delta V changes significantly with t(Bi-Te), t(Cu) and T. The effective thermo-emf Delta V-eff increases significantly with an increase of 1/T and exhibited a local maximum at 1/T = 1/240 s(-1). The resultant vertical bar alpha vertical bar and the effective temperature difference Delta T-eff were increased significantly by optimizing t(Bi-Te) and t(Cu) at 1/T = 1/240 s(-1). The power generation Delta W-eff (= Delta V-eff (2)/4R(calc)) estimated using the measured Delta V-eff and calculated R-calc also exhibited a local maximum at 1/240 s(-1) for an optimum combination of t(Bi-Te) = 0.1 mm and t(Cu) = 2.0 mm, so that the maxima Delta W-eff at 1/T = 1/240 s(-1) for the p-and n-type composites were 2.28 and 2.92 times higher than those obtained at 1/T = 0 s(-1). This significant increase in Delta W-eff is owing to both the increase in Delta T-eff and the increase in ZT due to the increase in vertical bar alpha vertical bar. The power generation was thus found to be enhanced significantly by imposing the alternating temperature gradients on touching Cu/Bi-Te/Cu composites.