Recently, a massive magnetocaloric effect near the liquefaction temperature of hydrogen has been reported in the ferromagnetic material HoB$_{2}$. Here we investigate the effects of Dy substitution in the magnetocaloric properties of Ho$_{1-x}$Dy$_{x}$B$_{2}$ alloys ($textit{x}$ = 0, 0.3, 0.5, 0.7, 1.0). We find that the Curie temperature ($textit{T}$$_{C}$) gradually increases upon Dy substitution, while the magnitude of the magnetic entropy change |$Delta textit{S}_{M}$| at $textit{T}$ = $textit{T}_{C}$ decreases from 0.35 to 0.15 J cm$^{-3}$ K$^{-1}$ for a field change of 5 T. Due to the presence of two magnetic transitions in these alloys, despite the change in the peak magnitude of |$Delta textit{S}_{M}$|, the refrigerant capacity ($textit{RC}$) and refrigerant cooling power ($textit{RCP}$) remains almost constant in all doping range, which as large as 5.5 J cm$^{-3}$ and 7.0 J cm$^{-3}$ for a field change of 5 T. These results imply that this series of alloys could be an exciting candidate for magnetic refrigeration in the temperature range between 10-50 K.
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