  Space photometric time series of the most massive members of the young open
cluster NGC 2264 allow us to study their different sources of variability down
to the millimagnitude level and permits a search for Slowly Pulsating B (SPB)
type pulsation among objects that are only a few million years old. Our goal is
to conduct a homogeneous study of young B type stars in the cluster NGC 2264
using photometric time series from space in combination with high-resolution
spectroscopy and spectropolarimetry obtained from the ground. The latter will
be presented in a separate follow-up article. We performed frequency analyses
for eleven B stars in the field of the young cluster NGC 2264 using photometric
time series from the MOST, CoRoT and Spitzer space telescopes and the routines
Period04 and SigSpec. We employ the MESA stellar evolution code in combination
with the oscillation code GYRE to identify the pulsation modes for two SPB
stars which exhibit short period spacing series. From our analysis we identify
four objects that show SPB pulsations, five stars that show rotational
modulation of their light curves caused by spots, one star that is identified
to be a binary, and one object in the field of the cluster that is found to be
a non-member Be star. In two SPB stars we detect a number of regularly spaced
pulsation modes that are compatible with being members of a g mode period
series. Despite NGC 2264's young age, our analysis illustrates that its B type
members have already arrived on the zero-age main sequence (ZAMS). Our
asteroseismic analysis yields masses between 4 and 6 Msun and ages between 1
and 6 million years, which agree well to the overall cluster age.
