Abstract This study describes equatorial region spatio-temporal variability of space source horizontal component of magnetic eld at the surface of the Earth using the data measured from ve INTERMAGNET magnetic observatory stations. The space source magnetic eld is extracted by subtracting mean of night time magnetic eld from the total horizontal component of the Earth 0 s magnetic eld. The magnetic eld which is mainly originated from the space has a great role in the dynamics of the ionosphere. Measuring magnetic eld in the magnetometer is relatively more accurate than measuring electric eld and the variation of the eld is an indicator for dynamics of the ionosphere. And this can give us a good approximation about dynamics of the ionosphere. The strength of the eld is high in between 10.00 hr and 13.00 hr local time. Dip latitudinal variation of day time horizontal component of Earth s magnetic eld is more signi cant than longitudinal variation of the eld in equator regions. As we go away from the dip equator the space source magnetic eld strength decreases. In AAE station the eld strength is maximum (dip latitude 1:8 ) followed by MBO (dip latitude 7:65 o ), GUA (Dip latitude 12:1 o o ), KOU (Dip latitude 16:89 ) and API (Dip latitude 29:9 o ) stations respectively. In AAE It displayed the highest amplitude, while in Apia obtained the lowest. And the space source magnetic eld exhibits spatio temporal variation in which the dip latitudinal variation of the space source magnetic eld dominates the longitudinal variation of day time magnetic eld strength in equator regions. This dramatic increment of the space source magnetic eld in AAE in all days, months and seasons could be due to high equatorial electron jet, high conductivity and electric eld strength in the dip equator. Unique way of 0 odetermining the day time strength of the electron jet is to observe the di erence in the magnitudes of the horizontal component of the magnetic eld between a magnetometer placed directly on the magnetic equator and one displaced out of it. Key words: Space source, Magnetic eld, Dip latitude, Spatio-temporal