Two interspecific hexaploid [2n=6x=78, 2(AD1)D2-1] fertile hybrids between two varieties of cultivated tetraploid species G. hirsutum [2n=4x=52, (AD1)] viz., MCU 5 and TCH 1609 and wild diploid species G. armourianum [2n=2x=26, D2-1] were synthesized by doubling the chromosome number of their respective F1 sterile triploid [2n=3x=39, (AD1)D2-1] hybrids using aqueous colchicine solution. Morphological and cytogenetic analysis confirmed the true nature of triploid and its hexaploid hybrids. The F1 triploid plants were intermediate in morphological characters and they were highly pollen sterile as well as self sterile. A maximum of 13 bivalents per PMC was recorded in G. hirsutum var. MCU 5 X G. armourianum triploid [2n=3x=39, (AD1)D2-1] but 10 I + 13 II +1 III was the most frequent meiotic configuration. In the triploid of G. hirsutum var. TCH 1609 X G. armourianum [2n = 3x = 39, (AD1)D2-1], maximum of 13 bivalents was recorded with an average of 11.08 bivalents, but 10 I + 10 II + 3 III and 13 I + 13 II were the most frequent meiotic configuration. The hexaploids [2n=6x=78, 2(AD1)D2-1] showed the expected features of the colchiploidised plants such as large sized flowers than triploids, increased pollen grain size, fertile pollen grains, boll and seed set with fibres as compared to the F1 sterile triploid plants. The hexaploid G. hirsutum var. MCU 5 X G. armourianum [2n=6x=78, 2 (AD1)D2-1] recorded maximum of 32 bivalents per PMC with most frequent meiotic configuration of 3 I + 25 II + 3 III + 4 IV. The maximum of 29 bivalents with an average of 24.96 bivalents per PMC was recorded in G. hirsutum var. TCH 1609 X G. armourianum hexaploid [2n=6x=78, 2 (AD1)D2-1], but 3 I + 28 II + 5 III + 1 IV was the most frequent meiotic configuration. The morphological and meiotic behavior of these hexaploid hybrids provided valuable information for their practical utilization in a cotton breeding programme.