'Kalki Mahâ-mantra' is the "Mahâ-mantra" for this Kaliyuga, which follows next to the other chanted "Mahâ-mantras". All the Mahâmantras are of high significance;  they are revealed by divine instrumentation at different times, depending on the era and need.

Mahâ means "great" and is used to identify with superiority, hence, Mahâ-mantra means - great mantra.

Before proceeding to the 'Kalki Mahâmantra' a brief description is made here about the significance of the Mahâmantras with an example from the 'Hare Krushna Mahâmantra':

Nâma-Mahâmantras (noble mantra based on the name of the supreme) are mantras for Moksha (liberation of the soul) and are meant for spiritual upliftment rather than attaining any material benefits or occult power. The mâhamantras, as opposed to other Tantric and Vedic mantras have no fixed rules of chanting. Tantric and Vedic mantras can be chanted only by following specific procedure and are used to invoke certain results, where as, the mâhamantras can be chanted by anyone, at any time or place. This invokes mercy from the God and the mantras get their potential from the Holy names of the supreme. The "Hare Krushna Mahâmantra", was given by the revered saint naamayogi avataar Chaitanya Mahaaprabhu (Guru of mahapurusha Achyutânanda and Panchasakhâ) and is: 

"Hare Krushna Hare Krushna, Krushna Krushna Hare Hare"
"Hare Râma Hare Râma, Râma Râma Hare Hare"

The "Hare Krushna Mahâmantra" consists of 16 syllables and is a plead to the Supreme God with its various names (Krushna, Râma). Its mention (of the different names of the divine) is made in Upanishads (significant literature of the Aryans those migrated to Bharat, i.e. India, and are valued only next to the Vedas; there are many different Upanishads also) as a saviour from sin (Kali santarana Upanishad). As the mâhamantra has been empowered by Chaitanya Mahaaprabhu, who is believed to be an incarnation of Sri Krushna, it is a potential mantra to invoke supreme mercy even for the dreaded sinners.

The 'Kalki Mahâmantra' follows the series of the liberating Mahâmantras and is given by Mahapurusha Achyutananda. The mantra is a liberating Mahamantra meant specifically for the last part of this Kali yuga. His disciple, beloved Baba Buddhanath Das here explains the significance of the Kalki Mahâmantra. The following is a part of the advice/talk given by Babaji on 7th Jan, 2003, at Garoi Ashram.

Please click here for a larger image (of the Oriya transcript shown below).