The NaZn13-type compounds La(Fe1-xCox)11.9Si1.1 (x=0.04, 0.06, 0.08) were successfully synthesized, in which the Si content is the limit that can be reached by arc-melting technique. TC is tunable from 243 to 301 K with Co doping from x=0.04 to 0.08. Great magnetic entropy change ΔS in a wide temperature range from ∼230 to ∼320 K has been observed. The adiabatic temperature change ΔTad upon changing magnetic field was also directly measured. ΔTad of sample x=0.06 reaches ∼2.4 K upon a field change from 0 to 1.1 T. The temperature hysteresis upon phase transition is small, ∼1 K, for all samples. The influence of Co doping on itinerant electron metamagnetic transition and magnetic entropy change is discussed.